GOP Sen. Jeff Flake: Trump can't win

Arizona Republican Sen. Jeff Flake says his party's presumptive nominee cannot win the general election.

"Let's face it: meet the old Trump, just like the new Trump," Flake said to reporters on Capitol Hill in the Senate hallway. "We've got what we've got. That's not somebody who can win the White House."

Flake has refused to support Trump, and he joins a filing rank of Republicans who have denounced the candidate's accusation that US District Judge Gonzalo Curiel has a conflict of interest in a class-action lawsuit over supposed fraud at Trump University.

Trump has said Curiel's Mexican heritage and his La Raza Lawyers of San Diego membership pose a conflict of interest because of his campaign promise to build a wall securing the US-Mexico border.

Flake now says one possible consequence Trump's comments on Curiel might be a challenge at the GOP convention in July.

"Where there's no talk of a convention challenge or anything else, this might spur it," Flake said.

Remarks of a possible contested convention from Sen. Flake come in addition to his previous anti-Trump comments made as a guest on MSNBC's Morning Joe on Monday.

"The whole thing that we Republicans say we're against, this identity politics, to say that if you're a certain gender or you're a certain race that you have to vote that way," Flake said. "He's just trying to confirm that stereotype that's completely wrong. It's offensive, it really is."

Flake spokesman Jason Samuels told CBS News on Tuesday that "prior to the judge comments, [Flake] publicly stated that he was holding out his support in the hopes that Trump would walk back some of his more controversial positions, especially the ban on Muslims entering the United States."