Christie: I never promised not to endorse Trump

Republican New Jersey Gov. Chris Christie on Sunday pushed back against claims that he had vowed never to endorse Donald TrumpDonald TrumpPost piles on: ‘Beyond debate’ Trump is unfit for office Clinton, Netanyahu have ‘in-depth’ conversation about US-Israeli ties NYT lays out argument against Trump for president MORE in the 2016 presidential race.

Christie, whose stunning endorsement of Trump on Friday has shaken up the 2016 race, was accused of breaking a vow that he would never back Trump by the publisher of New Hampshire’s largest newspaper.

In an interview with ABC's "This Week" on Sunday, Christie dismissed the claims from New Hampshire Union Leader Publisher Joe McQuaid.

"It's just not true. He called me two days after the [New Hampshire] primary and said, 'I was just told that you're about to endorse Donald Trump.' And I said to him, 'That's absolutely untrue. I'm not about to endorse anybody,'" Christie said.

McQuaid, whose publication had endorsed Christie, said he is "disappointed" in the former candidate’s support for Trump.

Christie was then pressed by ABC News host George Stephanopoulos about some of Trump’s most controversial campaign promises, including a ban on Muslims entering the United States and building a wall on the Mexican border.

“Donald Trump and I are not going to agree on every issue,” Christie said, adding, “I ran against the guy, so of course there are things I disagree with.”

Christie was unable to answer a question about how Trump would achieve these goals, particularly the Mexican wall, which has become a signature piece of his campaign.

“The fact is that he’s going to have to answer that question. He will,” Christie said.

The New Jersey governor also called Trump "dead wrong" on his plan to ban Muslims from entering the U.S.

"The idea of banning all Muslims from this country is ridiculous. And the reason it's ridiculous is because you don't need to do that to make America safe," Christie said. "When Donald Trump said that, he was dead wrong. And he's dead wrong now."