U.S. Rep. Justin Amash chose Independence Day to break with the Republican Party, decrying hyperpartisanship and saying he is “disenchanted with party politics and frightened by what I see from it.”

In an essay for the Washington Post, the fifth-term congressman representing the Grand Rapids area said the two-party system “has evolved into an existential threat to American principles and institutions.”

“Today, I’m declaring my independence and leaving the Republican Party,” Amash wrote on the Fourth of July.

“No matter your circumstance, I’m asking you to join me in rejecting the partisan loyalties and rhetoric that divide and dehumanize us. 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.”

The move comes after Amash became the sole GOP lawmaker in Congress to break with President Donald Trump over the findings of special counsel Bob Mueller’s report, saying Trump’s alleged conduct to obstruct justice warrants impeachment.

His decision had drawn condemnation by GOP leaders, and Amash had since attracted four challengers in the 2020 Republican primary, with the latest candidate, Peter Meijer, joining the race Wednesday.

The president was quick to react to the news on Twitter.

The independent-minded lawmaker had long clashed with party leadership.

An aide to the congressman confirmed Thursday that Amash will refile to run as an independent for his current seat.

Amash has spoken out in recent months about his long-simmering frustration with partisanship in Washington, even leaving the House Freedom Caucus he helped co-found in 2015.

Elected in the 2010 tea party wave, Amash has ranked among the most conservative members of the House, opposing what he calls runaway government spending and casting votes based on his libertarian principles and conscience.

Amash, 39, has said he’s not ruling out a third-party or independent bid for the White House, but has filed to run for reelection to Congress.

“Many would contend he left the Republican Party a long time ago, de facto, and all he’s doing is making it official,” said political analyst Bill Ballenger, a former GOP state lawmaker.

“It’s not as momentous as it might otherwise be if it were something you couldn’t see coming based on his behavior or record.”

The big question is what Amash does next — run for reelection to Congress as an independent or perhaps run for president.

“It appears to me that Justin Amash has little or no chance to return to Congress for the 3rd District of Michigan,” Ballenger said, referring to the challenges for independent and third-party candidates.

“Nobody can be sure what he’s going to do next, and he’s such a lone wolf that he’s not the kind of person you can see leading a movement. It’s not going to happen because Justin Amash has no following.“

David Dulio, a political scientist at Oakland University, said Amash’s GOP departure frees him from running in the crowded primary where Trump supporters might have sought to punish him.

“It’s usually much harder for an independent candidate to win in our system that, for all intents and purposes, is a two-party system,” Dulio said.

“Having said that, Amash will have the benefits that come with being an incumbent, and those will be helpful. He has a strong base of support in that district and that might be enough to carry him over the finish line.”

In the meantime, it’s unclear whether Amash will remain part of the House Republican caucus, said Kyle Kondik of the University of Virginia Center for Politics.

“Presumably, the leadership won’t want him anymore. If he is not in one of the two-party caucuses, I don’t think he will have any committee assignments,” he said.

Amash sits on the House Committee on Oversight and Reform.

Kondik said he revised UVA’s Crystal Ball rating for Michigan’s 3rd District from “likely” Republican to toss-up based on Amash’s announcement Thursday. 

“That rating is basically operating on the assumption he runs for another term. In the case he does not — and maybe at this point he may run for president — we would rate the race as ‘leans Republican,'” Kondik said. 

“It is a competitive district on paper although it’s also one that Republicans should win in most circumstances. This is an odd and unclear circumstance, though.”

In his essay, Amash, a former state lawmaker from Cascade Township, noted that both his immigrant parents were Republicans, and that he had supported GOP candidates and was elected to office as one.

“The Republican Party, I believed, stood for limited government, economic freedom and individual liberty — principles that had made the American Dream possible for my family,” Amash wrote.

But he says that Americans have let elected officials disregard the separation of powers, federalism and the rule of law, resulting in the consolidation of political power. He said congressional leaders expect lawmakers to act “in obedience or opposition to the president and their colleagues on a partisan basis.”

“The parties value winning for its own sake, and at whatever cost,” Amash wrote. “Modern politics is trapped in a partisan death spiral, but there is an escape.”

Bill Kristol, a political analyst, regular conservative voice on political talk shows such as ABC News’ “This Week” and co-founder of the now defunct conservative magazine The Weekly Standard, tweeted his views on Amash’s decision:

Amash argues that most Americans are not “rigidly” partisan and feel not well-represented by the two major parties.

“But we owe it to future generations to stand up for our constitutional republic so that Americans may continue to live free for centuries to come,” Amash said.

“Preserving liberty means telling the Republican Party and the Democratic Party that we’ll no longer let them play their partisan game at our expense.”

mburke@detroitnews.com