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

“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.”

Amash, perhaps the most fiscally conservative member of Congress, has increasingly been at odds with the GOP. In May, he became the first and only Republican in Congress to call for the impeachment of President Donald Trump. And in June, Amash stepped down from the once-ideologically conservative, now steadily more partisan House Freedom Caucus.

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.

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.”

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.”

“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 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.