“True to Washington’s fears,” Amash wrote, “Americans have allowed government officials, under assertions of expediency and party unity, to ignore the most basic tenets of our constitutional order: separation of powers, federalism and the rule of law. The result has been the consolidation of political power and the near disintegration of representative democracy.”

Amash pointed out that Washington said partisanship “opens the door to foreign influence and corruption, which finds a facilitated access to the government itself through the channels of party passions.”

In his op-ed Thursday, Amash quoted extensively from George Washington’s farewell address , in which the first president warns against political parties and calls partisanship the people’s “worst enemy.”

But Amash has always displayed a brand of politics that largely rejected a neat party definition ― whether it be Republican, Democratic or, most accurately, Libertarian.

“No matter your circumstance, I’m asking you to join me in rejecting the partisan loyalties and rhetoric that divide and dehumanize us,” Amash wrote in a Washington Post op-ed posted Thursday morning. “I’m asking you to believe that we can do better than this two-party system — and to work toward it. If we continue to take America for granted, we will lose it.”

Rep. Justin Amash is celebrating this Fourth of July in a manner years in the making: by declaring his independence from the Republican Party .

Bill Pugliano via Getty Images Rep. Justin Amash (R-Mich.) holds a town hall meeting on May 28 in Grand Rapids, Michigan. In an op-ed published Thursday, the congressman said he was leaving the Republican Party.

Amash has long shown discomfort with the trajectory of the Republican Party as it abandons its calls for fiscal conservatism in favor of Trump’s high deficits, as it places a sense of security over liberty, authoritarianism over limited government, and nativism, racism and xenophobia over equal opportunity.

Amash began his op-ed by pointing out that his father was a Palestinian refugee whom America welcomed. He said both his parents were Republicans, and he ran for office ― first as a state legislator in Michigan and then as a congressman representing the Grand Rapids area ― as a Republican.

“In recent years, though, I’ve become disenchanted with party politics and frightened by what I see from it,” Amash wrote. “The two-party system has evolved into an existential threat to American principles and institutions.”

Amash was already facing a primary challenge from a number of Trump-friendly Republicans, including state Rep. Jim Lower, state Rep. Lynn Afendoulis, former Sand Lake Village Trustee Tom Norton and potentially a number of other businessmen from the area.

He’ll now face reelection as an independent if he decides to try and keep his congressional seat. Amash has been cagey about running for president. “I haven’t ruled anything out,” he said in June.

In the meantime, GOP leadership will have to decide what they do with Amash and his one committee assignment on the Oversight and Reform panel. (Republican leaders kicked Amash off the Budget Committee at the end of 2012 for voting against their fiscal blueprints, and they’ve rejected the former lawyer’s pleas to be assigned to the Judiciary Committee.)

If they do bar him from caucusing with Republicans, Amash won’t be able to attend GOP conference meetings, and he may be stripped of his seat on the Oversight Committee.

Not that any of that seems to matter much to Amash. In the op-ed, he called out congressional leaders on both sides for “dangling” chairmanships, committee assignments, bill sponsorships, endorsements and campaign resources to compel members to vote with their party.

“Instead of acting as an independent branch of government and serving as a check on the executive branch, congressional leaders of both parties expect the House and Senate to act in obedience or opposition to the president and their colleagues on a partisan basis,” he wrote.

“Today, I am declaring my independence and leaving the Republican Party.”

Trump responded to the news in a tweet Thursday morning, repeating his mantra of “no collusion, no obstruction” and calling Amash “a total loser.”