White House spokesman Josh Earnest said Tuesday that Donald Trump's suggestion that Muslims should be barred from the United States disqualifies him from the presidency.

"What Donald Trump said yesterday disqualifies him from serving as president," Earnest said, noting that the first act any president must take is "swearing an oath to preserve, protect and defend the Constitution of the United States."

Earnest derided Trump's overall campaign approach.

"The Trump campaign for months now has had a dustbin of history-like quality to it, from the vacuous sloganeering, to the outright lies to even the fake hair, the whole carnival barker routine that we've seen for some time now," Earnest said. "The question now is about the rest of the Republican Party and whether or not they're going to be dragged into the dustbin of history with him; and right now the current trajectory is not too good."

Earnest mocked other Republican presidential hopefuls for pledging to back Trump, should he win the nomination, and the GOP leadership for embracing him.

He pointed to a recently leaked memo from the National Republican Senatorial Committee advising GOP candidates to "ride the Trump wave" as proof that the party is out-of-step with American values when they embrace Trump's xenophobic ideas.

Earnest's advice to Republicans is to abandon Trump.

"They should say right now that they would not support Donald Trump for president," he said about the Republican presidential field. "Republican candidates to stand by their pledge, that in and of itself is disqualifying," Earnest added.

"Any Republican who is too fearful of the Republican base to admit it has no business serving as president either," he said.

"There certainly has been an accumulation of offensive and incendiary comments from Mr. Trump, this is only the latest," Earnest said, referring to a litany of controversial comments from the real estate mogul and reality TV star, including his anti-Hispanic comments.

Earnest dismissed rebukes from other GOP nominees as meaningless unless they rescind their pledge to stand by him, should he win the nomination.

"Those comments don't mean that much if they're going to go ahead and vote for him … it's as simple as that," Earnest said. "If they're willing to walk the walk when it comes to the news releases or tweets submitted by their campaigns, then they should say so. [And] it shouldn't take that long. It's not that hard to analyze what Mr. Trump said."

Earnest said it comes down to potential party unity versus supporting the Constitution and the nation's founding principles.

"Do they have the courage of their convictions to stand up to Mr. Trump's supporters and say they are going to side with the Constitution over Mr. Trump, even if Mr. Trump is the Republican nominee?" Earnest asked. "If they don't have that much courage … then they have no business serving as president of the United States themselves."