2016 presidential candidate Sen. Bernie Sanders has long advocated for a publicly-funded Medicare For All program, arguing that Americans should not have to worry about hospital stays or if medical bills will bankrupt them. In 2017, the Vermont senator introduced the Medicare For All Act, which, if passed, would transition the country over to a Medicare For All system over the course of four years until eventually, "every man, woman and child in the country would be covered by Medicare For All."

After announcing he'd beat his battle with prostate cancer, Colorado Sen. Michael Bennet also revealed his intention to run for president in 2020 during an interview with CBS This Morning in early May. While Bennet has expressed support for creating a public health care option, he doesn't support Medicare for All. "We need to fix health care and make good on what Obamacare promised: affordable high-quality health insurance with a public option that will guarantee competition to every county in America and lower drug prices," the senator said in his campaign launch video. "And that's not Medicare for All because I don't think 180 million Americans want to give up the insurance they already have through their work or their union."

According to CBS News, Bennet supports a public option for health care while also giving consumers access to private insurances via Obamacare marketplaces.

After months of speculation, former Vice President Joe Biden officially joined the field of Democrats vying for the presidency in 2020. While he hasn't thrown his support behind Sanders' Medicare for All bill, Biden has proposed giving people the option to choose between a government-run insurance plan or obtaining a private plan, The Hill has reported. Under Biden's policy, everyone would have the option to buy into a public option plan for Medicare should they so desire, according to The Hill.

New Jersey Sen. Cory Booker has said he believes that "health care is a human right." So it's no surprise that he was one of many Democrats who opposed efforts to repeal the Affordable Care Act, which he reportedly called "a vital step in the right direction" in 2014.

Since then, Booker has supported legislation aimed at expanding Medicaid to create public health insurance plans on the Obamacare exchange. He also backed a bill seeking to cap insurance companies profits while increasing the affordability of quality insurance through expanded health care subsidies and tax credits. The senator is also among the supporters of Sanders' Medicare For All Act.

New York City Mayor Bill de Blasio entered the 2020 presidential race in mid-May. Earlier this year, he rolled out NYC Care, a program that guarantees health care to all residents of New York City no matter their ability to pay or citizenship or immigration status. According to ABC News, de Blasio said the program will include mental health services as well as primary, specialty, maternity, and pediatric care.

In an interview with MSNBC he touted the program as a public option that could be expanded and built upon to work for more than just New York City. "We recognized that obviously health care is not just in theory a right," he said. "We have to make it in practice a right."

Montana Gov. Steve Bullock announced his 2020 campaign in May. Much of his campaign platform has so far centered around campaign finance and pushing to get money out of politics so the full breadth of his healthcare ideas aren't yet known. However, he's spoken of fulfilling "the promise of universal healthcare" on his campaign website and as governor, he expanded Medicaid in Montana.

South Bend, Indiana, Mayor Pete Buttigieg has expressed support for a Medicare For All system that would provide government-sponsored universal health care. However, in a December interview with the Associated Press, he also acknowledged that he would be willing to settle for less in the short term.

Buttigieg later elaborated on that comment when he told PBS' Judy Woodruff last month that he prefers taking a "Medicare for all who want it" pathway toward universal health care.

"In other words, take a version of Medicare or something like it, make it available as a public option on the exchange," he explained. "And then if people like me are right, that this will over time become the most efficient and preferred means, then this will be a very natural glide path to a single-payer environment."

Like many of the Democratic 2020 presidential candidates, former Secretary of Housing and Urban Development Julián Castro has advocated for establishing a Medicare For All health care system. According to CNN, he told prospective voters that he believed "we need universal health care" and that "we should do Medicare for all in this country" during a January visit to Iowa. What's more, he told MSNBC's Chris Hayes in December that legislation regarding a Medicare For All policy would be the "first big domestic policy" bill he'd move on if elected president.

While Maryland Rep. John Delaney has said he believes "we should have universal health care," he's not a supporter of universal Medicare. Rather, Delaney has proposed leaving Medicare alone and instead, rolling Medicaid into an entirely new system. He told CNBC's John Harwood that this new system, which would result in a phase out of employment-provided insurance, would cover everyone "from when they're born to when they're 65," at which point they'd move to Medicare.

Under Delaney's proposed system, people could, presumably for a fee, add supplemental coverage to the standard coverage universally provided or opt out of government-provided insurance altogether and purchase private plans in exchange for a small tax credit.

While campaigning for reelection in 2018, Rep. Tulsi Gabbard argued that "all Americans should have access to affordable healthcare through Medicare or a public option." She went on to specify that "we must ensure universal health care and empower the government to negotiate with pharmaceutical companies to bring down the price of prescription drugs." As the representative for Hawaii's 2nd Congressional District, she has co-sponsored the House's Medicare For All Act. These ideas continue to be part of her 2020 presidential campaign platform.

As senator for New York, Kirsten Gillibrand has co-sponsored Sen. Sanders' Medicare For All Act, which, if passed, would establish a fully government-run health care system within four years. She has also co-sponsored The Basic Health Program Expansion Act of 2018, which seeks to expand the Affordable Care Act's Basic Health Program in an effort to increase access to affordable coverage by double the program's current income cap.

California Sen. Kamala Harris has said it was her mother's reliance on Medicare during her battle with cancer that spurred her to be "among the first senators" to support Sen. Sanders' Medicare for All Act in 2017. She's also supported Brian Schatz' Medicaid buy-in bill, which seeks to enable states to use an expanded Medicaid program to institute public health insurance plans on state exchanges.

In a New York Times op-ed published in December, she argued that health care should be a right, not a privilege.

Although it's unclear where former Colorado Gov. John Hickenlooper stands on things like universal or single-payer health care, he moved to expand Colorado's Medicaid program in 2013. That expansion enabled an estimated 160,000 residents to join the program, according to The Denver Post.

In 2017, the self-proclaimed moderate Democrat teamed up with two other governors, Ohio Republican John Kasich and Alaska Independent Bill Walker, to introduce a health care plan that included keeping the Affordable Care Act's federal individual mandate, reviewing regulations, and basing insurance costs on individuals' financial capacity, The Washington Post reported.

Washington Gov. Jay Inslee's 2020 presidential campaign has so far had more of a focus on climate change, so it's a little unclear where his campaign stands on health care. That being said, his work as governor has seen him push for a number of health care initiatives and policies. Earlier this year, for example, he joined a number of Washington's Democratic lawmakers in proposing legislation that, if passed, would introduce a public option health care plan to the state's health insurance exchange.

According to The Seattle Times, Inslee said the legislation was an attempt to put the state of Washington on the road to universal health care.

At a CNN town hall in February, Minnesota Sen. Amy Klobuchar said she believed the country ultimately needed to get to universal health care. However, she also discussed how she'd reform health care in the short term in an effort to work toward a universal health care system.

Speaking to voters at CNN's town hall, she advocated for expanding coverage by building on the Affordable Care Act through the creation of a public insurance option. What's more, she's co-sponsored Sen. Schatz' Medicaid buy-in bill, which would expand Medicaid to enable states to establish public health insurance plans on the Obamacare exchanges that had premiums capped at 9.5 percent of a household's income. (Sens. Booker, Harris, Gillibrand, Sanders, and Elizabeth Warren also co-sponsored this bill.)

Miramar, Florida, Mayor Wayne Messam announced his 2020 candidacy to CNN in late March. In an in-depth interview with WBUR, Messam said the issue of affordable health care was a personal one as his parents had "battled debilitating health issues in their latter years," causing him to see "firsthand the impacts that can have on a family."

However, in speaking to WBUR, Messam didn't propose a specific policy. Rather he said he found Sanders' Medicare for All "to be the simplest reform idea" but was "open to any reform measure that expands health care coverage for all people."

In April, Rep. Seth Moulton became the third Massachusetts politician to launch a 2020 campaign, according to Politico. On his website, the congressman states that "all Americans deserve health insurance that's affordable, that isn't tied to a job, and that covers all pre-existing conditions — no matter who you are." Moulton goes on to argue for creating competition within the market by establishing a public option, thereby giving people a choice between public and private health care system.

Since making his presidential campaign official, former Rep. Beto O'Rourke has retracted his support for Sanders' Medicare For All bill and instead championed an initiative known as Medicare for America. According to Slate, O'Rourke told voters in Iowa earlier this month that he was "no longer sure" if Sanders' Medicare For All plan would be "the fastest way" to universal health care.

The former Texas representative is now advocating for Medicare for America, which calls for enrolling all those currently on Medicaid and Obamacare plans into Medicare and then making Medicare a voluntary option for anyone else. The program would have no age stipulations and would, in place of abolishing them, cap out-of-pocket expenses and put premiums on a means-tested sliding scale. According to NY Magazine, this would make Medicare for America less of "a fiscal leap" than Sanders' Medicare for All.

Ohio Rep. Tim Ryan announced his 2020 candidacy in early April. According to The New York Times, he is a co-sponsor of the House's Medicare for All bill. In 2017, however, he told the New Republic that lawmakers should ditch the term "single-payer health care," arguing that voters "don't have any clue" what it is. In an interview with CNN's At This Hour, Ryan said he'd supported Medicare for All since 2007 but stressed that he thinks such a program must be worked toward in steps.

"I personally don't believe we need to take people off of their private health insurance if they enjoy it," he said. "We need to make sure there are protections there for them around pre-existing conditions and all of that." He suggested lowering the Medicare system down to age 50 or 55 and allowing small businesses with 50 employees or less to be able to buy into the Medicare system.

California Rep. Eric Swalwell announced his candidacy during an appearance on The Late Show with Stephen Colbert in April. In an op-ed published by NBC News before he announced his campaign, Swalwell said his support for a Medicare for All universal health guarantee was solidified after his infant daughter spent days in an ICU. "Americans deserve a health care system in which if you get sick you get seen, as well as one in which if you get seen, you don’t go broke because of it," he wrote.

But while he's a co-sponsor of the House's Medicare for All Act, the California Democrat told CNN he doesn't agree with the bill's proposal to end private health insurance. As part of the health care policy outlined in his op-ed, Swalwell also called for boosting funding for the National Institutes of Health in order to give them long-term budget certainty and invest in finding cures for insidious diseases like cancer, ALS, Alzheimer's, and cystic fibrosis within our lifetime.

In 2016, Donald Trump ran on a campaign that included a promise to repeal the Affordable Care Act as he believes it is hurting families, farmers, and small businesses. He later said his repeal plan would include policies to "take care of everybody" as "everybody has got to be covered," hinting at something that sure sounded a lot like universal health care.

While Trump hasn't quite managed to repeal the health care reform law in its entirety, he has been able to chip away at it through things like shortening enrollment periods and the repealing the individual mandate.

The Trump administration has also allowed insurance companies to offer more short-term plans, in addition to Association Health Plans. Association health plans aren't required to cover the essential health benefits that Obamacare mandated, like maternity care, according to Vox.

Trump has argued that repealing the Affordable Care Act and returning America to a health care system where insurance companies must compete for customers will bring about lower costs and higher-quality service. He's also characterized Democrats' Medicare For All bill as a threat to American seniors and an attempt to model the United States off Venezuela.

The Massachusetts senator was an avid supporter of the Affordable Care Act and she has continued to introduce legislation aimed at building on its progress. In 2018, for example, she introduced the Consumer Health Insurance Protection Act alongside Sens. Booker, Harris, Gillibrand, and Sanders. The bill seeks to increase the affordability of quality insurance by expanding health care subsidies and tax credits while also establishing a limit to insurance company profits. But Warren also supports universal Medicare and has endorsed the Medicare For All bill Sanders introduced in 2017.

While former Massachusetts Gov. Bill Weld hasn't officially thrown his hat all the way into the 2020 race just yet — he launched a presidential exploratory committee in February but has not officially launched a campaign — he's so far the only Republican to propose challenging Trump in the Republican primary.

For the moment, Weld's full views on health care remain unclear. However, while serving as Massachusetts governor in the 1990s, PBS has reported that Weld petitioned the federal government for funds to expand Medicaid in his state. Once he obtained those funds, he then relaxed Medicaid eligibility requirements to increase access to health care for many residents. And in 2016, he told The Washington Post that he supported introducing "more competition" to the insurance marketplace by allowing people to "shop across state lines."

Spiritual teacher Marianne Williamson has argued that "universal health care should be seen as the most natural thing in the world." However, her approach to health care also includes a focus on environmental, food, chemical and agricultural policies that, in her opinion, put corporations' profit ahead of Americans' health.

According to her website, her platform calls for "high-quality universal coverage for every American, including a medicare for all model" and includes advocating for reducing stigma around mental health and developing national policies geared at reduce stress levels.

Andrew Yang believes that "health care should be a basic right for all Americans" and his presidential platform includes a call for a single-payer health care system. While he's said he believes the Affordable Care Act "was a step in the right direction," he has argued that it failed to address two fundamental issues currently plaguing the nation's health care system: guaranteeing all citizens access to medicine and giving health care providers incentives aligned with providing efficient and quality care to patients. Yang has called for expanding Medicare to all or creating an entirely new health care system.

While a majority of the 2020 candidates agree on the need for universal health care, not all are behind a single-payer or Medicare For All system. What's more, 2020 candidates have diverging ideas on not only how to move the country toward universal heath care but how to pay for it.

While some advocate for Medicare For All, other candidates have leaned toward a Medicare-for-more approach while others support things like adding introducing more competition to the private marketplace or a public insurance option. Voters can be sure that candidates will continue to flesh out their health care policy ideas as we move farther into the 2020 presidential primary.

Clarification: This piece has been updated to more accurately describe association health plans.