FORT WORTH, Texas (Reuters) - Republican candidate Donald Trump on Friday won the endorsement on Friday of New Jersey Governor Chris Christie, who said the billionaire businessman had the best chance of beating Democrat Hillary Clinton in the Nov. 8 presidential election.
"The best person to beat Hillary Clinton in November on that stage last night is undoubtedly Donald Trump," Christie told a news conference a day after a Republican candidates' debate. He spoke at a news conference before a Trump rally in Texas.
Donald Trump is "rewriting the playbook," said Christie, 53, who until earlier this month was a Trump rival for the Republican Party nomination.
See Chris Christie on the campaign trail:
Chris Christie on the campaign trail
New Jersey Gov. Christie endorses former Republican rival Trump
Republican Presidential hopeful Governor Chris Christie of New Jersey speaks during the 2016 Republican Jewish Coalition Presidential Candidates Forum in Washington, DC, December 3, 2015. (Photo credit should read SAUL LOEB/AFP/Getty Images)
Republican presidential candidate New Jersey Gov. Chris Christie speaks during the Republican Presidential Debate, hosted by CNN, at The Venetian Las Vegas on December 15, 2015 in Las Vegas, Nevada. AFP PHOTO/ ROBYN BECK / AFP / ROBYN BECK (Photo credit should read ROBYN BECK/AFP/Getty Images)
THIS WEEK - 10/4/15 - Presidential candidate and New Jersey Governor Chris Christie appears on THIS WEEK WITH GEORGE STEPHANOPOULOS, airing on the ABC Television Network. (Photo by Ida Mae Astute/ABC via Getty Images)
Chris Christie, governor of New Jersey, waves while waiting for Pope Francis, not pictured, to arrive for a joint meeting of Congress in the House Chamber at the U.S. Capitol in Washington, D.C., U.S., on Thursday, Sept. 24, 2015. Pope Francis, the first pontiff to address U.S. Congress, is preaching to a less-than-harmonious congregation as he faces a Congress riven by disputes over issues closest to his heart: income inequality, immigration and climate change. Photographer: Pete Marovich/Bloomberg via Getty Images
MEET THE PRESS -- Pictured: (l-r) New Jersey Gov. Chris Christie appears on 'Meet the Press' in Washington, D.C., Sunday, Sept. 13, 2015. (Photo by: William B. Plowman/NBC/NBC NewsWire via Getty Images)
THE TONIGHT SHOW STARRING JIMMY FALLON -- Episode 0319 -- Pictured: (l-r) Governor Chris Christie during an interview with host Jimmy Fallon on August 31, 2015 -- (Photo by: Douglas Gorenstein/NBC/NBCU Photo Bank via Getty Images)
SQUAWK BOX -- Pictured: Governor Chris Christie in an interview on August 27, 2015 -- (Photo by: David Orrell/CNBC/NBCU Photo Bank via Getty Images)
NEW BRUNSWICK, NJ - AUGUST 25: New Jersey Governor and Republican presidential hopeful Chris Christie speaks at Chabad House at Rutgers University to express his opposition to President Obama's Iran deal on August 25, 2015 in New Brunswick, New Jersey. Christie also encouraged U.S. Senator Cory Booker (D-NJ) to oppose the deal. (Photo by Andrew Burton/Getty Images)
DES MOINES, IA - AUGUST 22: Republican presidential candidate New Jersey Governor Chris Christie tosses a pork burger on the grill at the Iowa Pork Producers Tent at the Iowa State Fair on August 22, 2015 in Des Moines, Iowa. Presidential candidates have a long tradition of making campaign stops at the fair. (Photo by Scott Olson/Getty Images)
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It was Trump's biggest endorsement from a mainstream Republican to date. The front-runner in the race, Trump, 69, has never held public office and has campaigned as a political outsider.
The endorsement of the New Jersey governor gives Trump, from neighboring New York, a lift ahead of next week's crucial Super Tuesday nominating contests.
Trump, a brash former reality TV show host, has now won three straight nominating contests in New Hampshire, South Carolina and Nevada, convincing some mainstream Republicans that he may have too much momentum to be stopped, especially if he wins big in the key southern U.S. primaries on Tuesday.
Former Secretary of State Hillary Clinton is battling U.S. Senator Bernie Sanders of Vermont for the Democratic nomination.