If John Kasich Goes Up Against Clinton...

A lot of Republicans have questioned why John Kasich is still running for president, given that it's mathematically impossible for him to win the nomination without a brokered convention. Kasich, though, has justified his continued candidacy on the grounds that he's the only Republican who can beat Hillary Clinton in November. Is he right? Can John Kasich beat Hillary Clinton in a general election?

If the polls are any indication, he sure can. No less than six surveys from March show Kasich defeating Clinton in a hypothetical match-up. Some polls give him a modest four-point lead, while others show him ahead of Hillary by double-digits. But Kasich's average lead over Clinton, as calculated by RealClearPolitics, is 6.5 points — not enormous, but still well outside the margin of error in most polls.

It's not too hard to explain this. Kasich, to his credit, is one of the few candidates who has run a genuinely positive campaign. He's attacked his opponents on occasion, sure, but these attacks haven't been especially vicious or personal. Moreover, he uses optimistic language rather than fear-mongering, and generally adopts an upbeat, happy demeanor. Compare this to Ted Cruz, who recently claimed that "the world's on fire" — while talking to a 3-year-old. In a campaign that's been replete with gloom and doom, Kasich's optimism is refreshing.

But alas, Kasich probably won't defeat Hillary, because he probably won't become the Republican nominee.

Kasich has only won a single state, and that's Ohio, where he's the governor. But he's trailing very badly in delegates — so badly, in fact, that even if he won every single remaining delegate in the primary, he'd fall short of the 1,237 required to win the Republican nomination. Of course, Kasich could — and will — make a play for the nomination if the convention is contested. But this requires convincing individual delegates to vote for him on the second ballot, and early signs suggest that he'll have a hard time doing this. Lastly, it's possible (and likely, if you ask me) that Donald Trump will run a third-party candidacy if he doesn't get the nomination, and that would almost certainly split the Republican vote and hand the presidency to the Democrats.

Kasich's dilemma illustrates perfectly why Republicans are unlikely to win the White House any time soon. For a variety of reasons, the GOP has steadily become more and more conservative over the last four decades or so. This is true both of the party's elected officials and its base voters, and the result is that it's more or less impossible to win a Republican primary without taking extremely far right positions on at least a few token issues, most notably immigration.

However, the country itself is moving in the opposite direction. There are a number of theories as to why this is, but opinion polls on everything from gay marriage and marijuana legalization to financial regulation and corporate taxes suggest that Americans, generally speaking, support liberal and moderate policies over conservative ones. The result is that the only way to win a Republican primary is to be so conservative that you're almost guaranteed to lose a general election.

Mitt Romney discovered this firsthand in 2012, when he advocated for the draconian policy of "self-deportation" as a means of dealing with illegal immigration. Romney said this, in part, to give him an edge over opponent Rick Perry, who has some moderate views on immigration, in the Republican primary. This helped Romney defeat Perry and win the nomination. It also ensured that Latino voters would turn out in record numbers in the general election and vote overwhelmingly for Barack Obama. After the election, RNC chair Reince Priebus admitted that Romney's endorsement of self-deportation hurt the party.

John Kasich is indeed the Republican with the best chance of defeating Hillary Clinton in a general election. And that's exactly why he won't win the nomination.