Rep. Justin Amash Justin AmashInternal Democratic poll shows tight race in contest to replace Amash Centrist Democrats 'strongly considering' discharge petition on GOP PPP bill On The Trail: How Nancy Pelosi could improbably become president MORE (Mich.), a vocal critic of President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE who left the GOP last week, said Sunday he's not ruling out a presidential run.

Amash told Jake Tapper Jacob (Jake) Paul TapperThe media's misleading use of COVID-19 data Julia Louis-Dreyfus: 'We can't spend much time grieving' Ginsburg Pence aide dismisses concerns rushed vote on Trump nominee will hurt vulnerable senators MORE on CNN's "State of the Union" he would consider running as an independent.

"I still wouldn't rule anything like that out. I believe that I have to use my skills, my public influence, where it serves the country best. And I believe I have to defend the Constitution in whichever way works best," he said. ADVERTISEMENT

Amash announced in a Washington Post op-ed Thursday that he was leaving the Republican Party.

He had been the only member of the GOP to call for impeachment proceedings against President Trump.

In his op-ed, Amash did not specifically call out Trump.

He told CNN on Sunday that he has had concerns with the Republican Party for several years and that "this term in Congress has really shown how bad it can get."

Amash said he plans to run for reelection to his congressional seat and is "very confident" he will win despite leaving the party.

He faces a Republican challenger, Jim Lowe.