Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

New Jersey Gov. Chris Christie offered up the latest twist of the Republican presidential primary when he endorsed Donald Trump on Friday, saying the GOP frontrunner is "rewriting the playbook of American politics."

The backing from his vanquished primary opponent came the day after Trump found himself under fierce attack from Sens. Marco Rubio and Ted Cruz in the final debate before next week’s critical Super Tuesday nominating contests.

“The single most important thing for the Republican Party is to nominate the person who gives us the best chance to beat Hillary Clinton,” Christie said at a news conference in Fort Worth, Texas. “I can guarantee that the one person Hillary and Bill Clinton don’t want to see on that stage come next September is Donald Trump.”

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

“He is rewriting the playbook of American politics because he is providing strong leadership that is not dependent upon the status quo. The best person to beat Hillary Clinton in November is undoubtedly Donald Trump,” Christie added.

Trump, who previously dismissed the importance of endorsements, said Christie is “the one endorsement that I felt very strongly about.”

Trump campaign acting like a front running juggernaut. Having the Christie endorsement ready the day after the Rubio attack is pretty smart — Chuck Todd (@chucktodd) February 26, 2016

Christie exited the presidential race after a disappointing finish in the New Hampshire Republican primary earlier this month. He is Trump's most high-profile endorsement to date, and his support comes four days before the important Super Tuesday primaries and caucuses are held in 13 states.

The two focused their attention on Rubio during the joint news conference. The Florida senator aggressively went after Trump during Thursday night’s debate and at a rally hours before the endorsement.

Lightweight Marco Rubio was working hard last night. The problem is, he is a choker, and once a choker, always a choker! Mr. Meltdown. — Donald J. Trump (@realDonaldTrump) February 26, 2016

“Desperate people do desperate thing,s” Christie said of Rubio. He likened the new lines of attack to "flailing punches in the last days of a losing campaign.”

“The idea that Marco Rubio can get inside Donald Trump’s head is an interesting proposition, but one that is really for the D.C. parlor game,” he added.

It was Christie who spurred Rubio’s lowest moment of the campaign when, during the final debate before the Granite State primary, he attacked Rubio for his reliance on talking points. Since then, Trump has repeatedly said Christie “destroyed” Rubio in a debate and has attempted to brand his rival as a “choke artist.”

Cruz campaign aide tells me, re: Christie/Trump: "New Jersey values joining up with New York values" — Hallie Jackson (@HallieJackson) February 26, 2016

When he was in the race, Christie aggressively attacked Rubio and Ted Cruz for being junior U.S. senators unready to lead as president. He also knocked Trump for lacking policy depth.

But on Friday he dismissed those criticisms as nothing more than two the product of two competitors running for the same job.