Only two presidents have been impeached in U.S. history — Andrew Johnson in 1868 and Bill Clinton in 1998. And opponents of Donald Trump certainly hope he'll be the third in line. But who can impeach Trump? The answer, as always, is Congress.
The first step would be for members of the House of Representatives to introduce the charges for impeachment to the Judiciary Committee. The committee would then decide whether or not to pursue the charges; if the decision is to move forward, the full House would subsequently hold a vote. A simple majority would have to vote in favor of continuing the procedure, which would then move to the Senate, where a majority of two-thirds would have to cast their votes supporting the president's removal.
Democrats certainly seem ready for it. On Monday, Texas Rep. Al Green issued a statement explicitly calling for the president's impeachment; California Rep. Maxine Waters has repeatedly pledged her commitment to removing Trump from office. "The President is a liar, his actions are contemptible, & I'm going to fight everyday until he's impeached," Waters tweeted in April. But given that Republicans currently make up the majority in both the House and the Senate, the impeachment of President Trump is highly improbable and will likely remain so, at least until Democrats take control of Congress.
The recent news of Trump's decision to share classified information with Russian officials has sparked some of the most intense scrutiny and criticism since he took office, but so far, it seems that he did not break the law. Professor Michael Gerhardt, who teaches constitutional law at the University of North Carolina, told People that more evidence would be necessary to successfully impeach the president. "The critical thing that those congressmen will have to show is that he’s done something that will qualify as treason, bribery, or other high crimes and misdemeanors," he said. Professor Christopher Peterson, a law professor at the University of Utah, opined that there is no "clear smoking gun" with which to charge Trump as of yet.
Still, there is one hopeful sign for those in support of Trump's impeachment: Professor Allan Lichtman, who teaches at the American University and has accurately predicted the results of every presidential election for over 30 years, told the Washington Post in September that, were he elected, Trump would ultimately be impeached. He wrote a book on what he believes is Trump's inevitable firing.