New Jersey Governor Chris Christie endorsed billionaire Donald Trump on Friday, throwing his support behind the other brash-talking Republican candidate from the New York area and calling him the only man in the race qualified to be president.

“The best choice is Donald Trump. There was no choice in my mind," said Christie, standing beside Trump at an event in Fort Worth, Texas. Christie ended his candidacy for president Feb. 10 after losing badly in New Hampshire.

"When I was running for president, I wanted to beat him and he wanted to beat me," Christie said. "But that part of the conversation is over. The question is, who is the best person to stop Hillary Clinton getting back into the White House? This is the best person."

New Jersey Governor Chris Christie announces his support for Republican presidential candidate Donald Trump on Feb. 26, 2016, in Fort Worth, Texas.
New Jersey Governor Chris Christie announces his support for Republican presidential candidate Donald Trump on Feb. 26, 2016, in Fort Worth, Texas.
Photographer: Tom Pennington/Getty Images

Trump said, "To me, it's a very big endorsement. Generally speaking I'm not big on endorsements. This was one endorsement that really meant a lot. Chris is an outstanding man, with an outstanding family. He's done a great job, and I think this is the one endorsement that I felt very strongly about that I wanted to get."

Trump said that he and Christie did not discuss any future position in a possible Trump White House administration, and Christie said he was not offered one. Christie worked as a federal prosecutor before becoming New Jersey governor but can't run again for governor because of term limits. Christie said he intends to serve his full term, then go into the private sector.

Christie quickly showed his value to the Trump campaign, and his likely role: attack dog. He tore into Florida Senator Marco Rubio repeatedly at the announcement, after Rubio went on the attack against Trump at a debate on Thursday night in Houston. 

"It’s one act after the other," Christie said of Rubio. "We don't need any more of these Washington, D.C. acts. The problem is Washington, D.C., and we don’t need Washington politicians to come in and fix it ."

Rubio sought to turn the Christie endorsement back on Trump, telling reporters that after his tough questioning of Trump in the debate, "Donald probably needs a life-line after last night, so he called in Chris Christie."

As for Trump, Rubio said, "he’s a con man. I think it’s time to unmask him for what he is. He’s trying to take over the conservative movement even though he’s not a conservative. But more importantly he’s a con. I mean, he is a con man who is taking advantage of people’s fears and anxieties about the future, portraying himself as some sort of strong guy. He’s not a strong guy."

Trump joined the fray, saying Rubio is so nervous and shaky that he's not fit to be president.

"I watched a part of his little act and he’s a desperate guy. He’s a nervous nelly," Trump said. "I watched him backstage. He’s a mess. I've never seen a human being sweat like this man sweats."

Trump added; "Once a choker, always a choker. ... Marco Rubio is a lightweight, he doesn't have the talent, he doesn't have the temperament, he can never make us great."

Christie has attacked Rubio before, tearing into him on a New Hampshire debate stage earlier this month for saying canned lines over and over. Rubio was knocked off stride, repeating the same sentence three times, and has had to work hard to recover.

Christie stayed behind after the news conference to introduce Trump at a rally with voters, calling him the next president of the U.S. Trump's campaign said Christie will appear at a Trump rally in Oklahoma City on Friday night. 

Immediately after the Trump-Christie announcement, Ohio Governor John Kasich issued a news release about an endorsement of his own: former New Jersey Governor Christine Todd Whitman.

Friday's appearance wasn't disclosed by Christie's' staff; a routine media update issued less than 24 hours earlier noted that Christie and his lieutenant governor, Kim Guadagno, would have no public schedule.

Christie hasn't held a news conference since quitting the race more than two weeks ago. At his only scheduled public appearance, at a school ribbon-cutting ceremony in Newark on Feb. 24, he left before the event's end, and as reporters set off to try to meet him at his car, school security guards blocked their access to hallways.

Polls suggest Trump has a significant lead heading into the 11 contests where Republicans will award delegates on March 1, known as "Super Tuesday." A Bloomberg Politics poll of seven southern states that will vote on Tuesday showed Trump leading with 37 percent of likely Republican voters. Rubio and Senator Ted Cruz of Texas were tied in second with 20 percent, according to the poll, which was conducted Feb. 22-24.

Anthony Carbonetti, a Manhattan-based Christie fundraiser and one-time chief of staff to former New York Mayor Rudolph Giuliani, said he wasn't surprised that Christie endorsed Trump, even as some of his top donors went to Kasich.

"Christie's always been the guy that does things his own way," Carbonetti said. "He made a decision as to who he thinks will be the best candidate."

Carbonetti said he's not currently supporting any candidate, but he had nice things to say about Trump.

"I don’t know Cruz at all. I've met Marco Rubio. Donald I've known for 25 years. You know Donald, you can't help but like him, he's a very likable guy," Carbonetti said.

As for Christie donors turning to Kasich after Christie dropped out, Carbonetti said Trump might indeed need their money down the road, in a general election where the price tag could easily surpass $1 billion. In the primary contests, Trump is largely funding his own campaign.

Both Rubio and Cruz stepped up their attacks at the debate Thursday. Earlier Friday, Rubio continued attacking Trump at a campaign rally in Dallas. "It's time to pull his mask off so people can see what we're dealing with here, and what we're dealing with is a con artist," Rubio said. "He made his entire career sticking it to the little guy."

Trump has used high-profile endorsements to dominate news cycles before significant contests. Just ahead of the Feb. 1 Iowa caucuses -- where he placed second behind Cruz -- Trump announced he'd received the endorsements of Sarah Palin and evangelical leader Jerry Falwell Jr.

-- With assistance from Elise Young, Zachary Mider, and Michael C. Bender.

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