For a little while, Michigan congressman Justin Amash was the lone Republican calling on Congress to start impeachment proceedings against Donald Trump. Then, last week, he left the party altogether, announcing in a July 4 op-ed for The Washington Post that he was leaving the GOP and declaring himself an independent, characterizing the U.S. government as being in a "partisan death spiral."

His position on impeachment puts him at odds not only with his own former party but also with Democratic House speaker Nancy Pelosi. Since the release of the Mueller report, at least 80 House Democrats have come out in support of an impeachment inquiry against the president, but Pelosi has dismissed those calls, saying instead that Trump is "becoming self-impeachable in terms of some of the things he’s doing."

Amash followed up the announcement of his leaving the party by appearing on CNN's State of the Union with Jake Tapper on Sunday. He told Tapper that Pelosi's refusal to open impeachment hearings was a mistake:

"From a principled, moral position, she's making a mistake. From a strategic position, she's making a mistake. If she believes, as I do, that there's impeachable conduct in there, then she should say so. She should tell the American people: We're going to move forward with impeachment hearings and potentially articles of impeachment."

Amash started calling for impeachment proceedings against Trump in May, when he tweeted, "America’s institutions depend on officials to uphold both the rules and spirit of our constitutional system even when to do so is personally inconvenient or yields a politically unfavorable outcome." Then a photo circulated online of him lecturing students on the Capitol steps about why such proceedings should begin. It's a seemingly strange move for a Tea Party Republican, especially one who helped found the far-right Freedom Caucus in 2010, which he was forced out of after promoting an impeachment inquiry. But Amash claims he believes that Trump should be impeached based on the findings of Robert Mueller's two-year-long investigation, and his outspokenness on the issue seems to have precipitated his departure from the GOP.

Just beginning impeachment proceedings wouldn't be enough to remove Trump from office. Should the House actually vote to impeach him, the effort would likely get stonewalled in the Republican-controlled Senate, even if Majority Leader Mitch McConnell allowed an actual vote to take place. In an interview with Maureen Dowd for The New York Times, Pelosi explained her reasoning, saying of Trump: "He'd rather not be impeached. But he sees a silver lining. And he wants to then say, 'The Democrats impeached me but the Senate'—he won’t say Republicans—'exonerated me.' The thing is that, he every day practically self-impeaches by obstructing justice and ignoring the subpoenas."

Meanwhile, Amash has little faith that the majority of Congress is actually aware of the contents of Mueller's report, which our own Jay Willis has called "an invitation to Congress to impeach Trump." When Tapper asked how many of his Republican colleagues have likely read the report, Amash said, "I think it's probably less than 15 percent. And I'd say that's probably the case on both sides of the aisle."