(CNN) Former US Rep. Joe Walsh is ending his uphill challenge against Donald Trump for the 2020 Republican presidential nomination, after suffering a crushing loss in the Iowa GOP caucuses in which he received only 1% of the vote.

"I am ending my candidacy for president of the United States," Walsh told CNN's John Berman on "New Day." "I got into this because I thought it was really important that there was a Republican -- a Republican -- out there every day calling out this president for how unfit he is."

Walsh, a conservative, said he will do whatever he can to stop Trump, including help any of the Democratic candidates get elected.

Trump "literally is the greatest threat to this country right now. Any Democrat would be better than Trump in the White House," he said.

He accused the Republican Party of being a "cult" and said Trump can't be beat in the GOP primary "so there's no reason for me, or any candidate, really to be in there."