Republican Sen. Jeff Flake said President Donald Trump will likely face an independent challenge in the next presidential election, if not a challenge from within the party. The Arizona senator appeared on ABC's "This Week" on Sunday, Dec. 24.

Flake has been very critical of President Trump, even while supporting parts of his agenda, like the new tax cuts. Trump denounced the senator after Flake chose not to seek re-election.

Flake wouldn’t say what it would take for him to leave the Republican Party, but said if the party continues on the path of people like Roy Moore and Steve Bannon, people will leave.

“I think you’ll have a lot of people realize there’s no future for them in this party," Flake said. "I know a lot of them. Some are family members. Some are Republicans I’ve known for a long time.”

When asked whether he might run for president in 2020, Flake said he doesn’t rule anything out, but it’s not in his plans.