LANSING (AP) — Rep. Justin Amash of Michigan said Wednesday he is seeking the Libertarian nod for president because millions of Americans do not feel well represented by either major political party and their standard-bearers: President Donald Trump and presumptive Democratic nominee Joe Biden.

Amash, a Trump critic who left the Republican Party to become an independent and later supported his impeachment, told The Associated Press that too many people vote Republican or Democrat because they do not feel they have any other choice.

“It’s important that we present them with that alternative. … The first step to moving toward no political parties or all independent candidates is to provide some big challengers to the main two parties right now,” he said. “The Libertarian Party can be that challenger.”

But third-party presidential campaigns can have unpredictable consequences. In 2000, Ralph Nader’s Green Party presidential bid cost Al Gore crucial support and was a contributing factor in George W. Bush’s eventual win. Hillary Clinton’s 2016 loss, meanwhile, has been blamed in part on the support Green Party candidate Jill Stein picked up in crucial battlegrounds such as Pennsylvania.

Amash was elected in 2010 as part of the tea party wave that toppled Democratic control. If Libertarians select him as their nominee at a national convention currently scheduled for May 21-25 in Texas, he would face nearly impossible odds of winning the presidency.

But Amash argued there is “no clear-cut answer” about whether he would take support from Trump or Biden, especially in closely contested places like his home state of Michigan.

Trump narrowly won Michigan in 2016, by 10,704 votes.