Rep. Justin Amash of Michigan will seek the Libertarian Party’s nomination for president, ending months of speculation that the former Republican would run as an alternative to President Trump and presumptive Democratic nominee Joe Biden.

“Americans are ready for practical approaches based in humility and trust of the people,” Amash (I-Mich.) tweeted Tuesday evening. Two weeks earlier, he had tweeted that he was looking “closely” at a run, after denouncing a comment Trump made about presidential authority.

Amash, who turned 40 this month, was elected in the 2010 tea party wave and grew increasingly distant from Republicans as the decade went on, fending off a primary challenge from a business-backed conservative in 2014. He was deeply critical of Trump’s 2016 campaign, and even more critical of what the GOP did with control of the legislative and executive branches.

“Things have really taken a turn for the worse, in terms of the growth of libertarianism in Congress,” Amash told The Washington Post in a 2018 interview. “You have some bright spots here and there. But for the most part, the party’s become more nationalistic, more anti-trade.”

In 2019, Amash became the only Republican to call for Trump’s impeachment. Not long after, he left the party and continued to vote against spending bills, while opposing many White House priorities. He faced a tough reelection in his Grand Rapids, Mich.-based district, with Republicans and Democrats both filing against him.

At the same time, Amash faced pressure from members of the Libertarian Party to run for its nomination. The party hit a record high of nearly 4.5 million votes in 2016, with former New Mexico governor Gary Johnson leading the ticket. But there was no obvious favorite for this year’s nomination, with former Rhode Island governor Lincoln Chafee ending his bid this month and former judge Jim Gray, the party’s 2012 nominee for vice president, probably their best-known candidate.

Johnson welcomed Amash’s candidacy.

“I think it’s terrific,” Johnson said in a text message. “I’d have to think that his candidacy will garner a lot of attention, which will be great for the Libertarian Party.”

It’s unclear whether a bid by Amash would have a greater effect on Biden or on Trump. In 2019, a Detroit News poll found Biden leading Trump in Michigan, a state that has grown more uncertain for the president, by 12 points. With Amash as an option, Biden’s lead shrunk to six points, with some independents and Republicans moving away from the Democrat. But national polling of Amash has been sparse, and it’s unclear how many states the Libertarian Party will attain ballot access in as the coronavirus pandemic makes traditional signature-gathering impossible.

The Libertarian Party is set to meet in Austin over Memorial Day weekend to pick its presidential nominee, with the convention making its choice on May 25. While the pandemic has canceled many political events, the Libertarian Party had not moved the convention, and earlier this week Texas Gov. Greg Abbott announced that the state would “reopen” on May 1.