In a series of tweets this afternoon, Justin Amash accused President Donald Trump of having “engaged in impeachable conduct.” The libertarian-leaning Michigan congressman blamed his fellow Republican legislators for choosing to defend the president rather than the Constitution in the wake of Special Prosecutor Robert Mueller’s report.

“Mueller’s report reveals that President Trump engaged in specific actions and a pattern of behavior that meet the threshold for impeachment,” Amash tweeted. “In fact, Mueller’s report identifies multiple examples of conduct satisfying all the elements of obstruction of justice, and undoubtedly any person who is not the president of the United States would be indicted based on such evidence.”

Since the release of the Mueller report, most Republicans have circled the wagons around Trump. Senate Majority Leader Mitch McConnell (R–Ky.) has declared “case closed” on the Mueller investigation. Top-notch Trump sycophants like Sen. Lindsey Graham (R–S.C.) have gone further, claiming that “the president never did anything to stop Mueller from doing his job,” despite ample evidence to the contrary.

House Speaker Nancy Pelosi (D–Calif.) initially ruled out impeaching Trump, but she said last week that “every day gives grounds for impeachment.” Rep. Rashida Tlaib (D–Mich.) extended an invitation via Twitter for Amash to co-sponsor her resolution calling for a House investigation into impeachment.

Amash added that few members of Congress, on either side of the aisle, even bothered to read the Mueller report before coming to their conclusions about it.

Amash also took aim at Attorney General William Barr. Amash said Barr had “deliberately misrepresented” Mueller’s findings—presumably referring either to Barr’s letter to Congress in the days prior to the report’s release or to his subsequent testimony to the Senate Judiciary Committee on April 29. (Barr refused to appear before the House Judiciary Committee, as scheduled, the following day.)

Amash, who has frequently and publicly disagreed with members of his own party since Trump took office, is the first Republican since Mueller’s report came out to make such an open, public statement about being open to impeachment.

The report stops short of saying the president had obstructed justice, but it also does not exonerate Trump. “If we had confidence after a thorough investigation of the facts that the President clearly did not commit obstruction of justice, we would so state,” the report reads.

Indeed, the entire second volume of the 400-plus page report is dedicated to documenting incident after incident where the president attempted to interrupt, stop, or inhibit Mueller’s investigation into the ties between Trump’s campaign and the Russian government. Those attempts to “influence the investigation were mostly unsuccessful,” the report states, but only because “the persons who surrounded the President declined to carry out orders or accede to his requests.”

As I wrote at the time, Mueller was clearly—and correctly—kicking the question of obstruction (and the associated question of impeachment) to Congress. As I also wrote at the time, “intense partisanship will save the president from the political reckoning he probably deserves,” though choosing not to impeach Trump could set a dangerous precedent of its own.

Amash struck the same note on Sunday.

“While impeachment should be undertaken only in extraordinary circumstances, the risk we face in an environment of extreme partisanship is not that Congress will employ it as a remedy too often but rather that Congress will employ it so rarely that it cannot deter misconduct,” he wrote. “When loyalty to a political party or to an individual trumps loyalty to the Constitution, the Rule of Law—the foundation of liberty—crumbles.”