Congressman Justin Amash (I., Mich.), who left the Republican party last year after breaking caucus ranks by calling for President Trump’s impeachment, said Monday that he is considering a White House run as an independent.

“Americans who believe in limited government deserve another option,” the libertarian-leaning congressman tweeted, following comments from Trump about presidential authority during the coronavirus press conference. In a reply to a supporter, he then added, “Thanks. I’m looking at it closely this week.”

Thanks. I’m looking at it closely this week.

— Justin Amash (@justinamash) April 14, 2020

The Libertarian Party is planning to nominate a candidate for president on May 25 at its convention in Austin, but has struggled to attract a well-known candidate. Former Rhode Island governor Lincoln Chafee, who joined the party last year, abandoned a bid for the nomination earlier this month.

Former Massachusetts governor Bill Weld, who ran with Gary Johnson on the 2016 Libertarian ticket, returned to the Republican Party last year to run a primary campaign against Trump, which ended in March.

Amash, who is up for reelection, has repeatedly declined to publicly rule out a 2020 run.

“I’ve said many times, I don’t rule things like that out,” Amash said last June during a town hall, after becoming the first GOP member to say President Trump should be impeached over the conduct outlined in the Mueller Report. “If you’re fighting to defend the Constitution, if you find a way to do that that’s different and maybe more effective, then you have to think about that.”

Libertarian/conservative advocacy groups Club for Growth — Amash’s biggest past campaign donor — and FreedomWorks, which awarded him a “FreedomFighter” award for all of his first eight years in Congress, both said earlier this year that they would not support his House reelection efforts.