CHARLESTON, S.C./WASHINGTON (Reuters) - Republican candidate Jeb Bush was endorsed by former rival Senator Lindsey Graham of South Carolina on Friday, winning an important ally in a state where a Feb. 20 vote could prove critical in the 2016 race for a presidential nominee.
The move by the hawkish Graham, who ended his own presidential campaign on Dec. 21, reflected his view that Bush offered the best plan to defeat Islamic State militants and to do so by forming alliances with Muslim nations in the region.
Graham's decision could be significant in swaying not only South Carolina Republican voters but also his good friend Senator John McCain, the 2008 Republican presidential nominee who remains an influential figure in the party and who has spoken warmly about Bush in recent months.
Graham said the vote in South Carolina, which will follow Iowa's caucuses on Feb. 1 and New Hampshire's primary on Feb. 9, will reset the race.
"Jeb Bush is going to be a nominee that can win an election that as a party we can't afford to lose. He will be the president that can reset the world, bring us together and solve hard problems," Graham said.
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South Carolina's Graham to endorse Jeb Bush in 2016 White House race
NORTH CHARLESTON, SC - JANUARY 15: Former Republican presidential candidate and South Carolina Sen. Lindsey Graham (R) announces his endorsement of Jeb Bush for president on January 15, 2016 in North Charleston, South Carolina. Graham dropped his bid for the presidency last month. (Photo by Scott Olson/Getty Images)
NORTH CHARLESTON, SC - JANUARY 14: Republican presidential candidates (L-R) New Jersey Governor Chris Christie and Jeb Bush laugh during a commercial break during the Fox Business Network Republican presidential debate at the North Charleston Coliseum and Performing Arts Center on January 14, 2016 in North Charleston, South Carolina. The sixth Republican debate is held in two parts, one main debate for the top seven candidates, and another for three other candidates lower in the current polls. (Photo by Scott Olson/Getty Images)
GRINNELL, IA - JANUARY 12: Republican presidential candidate Jeb Bush greets people during a town hall at the Brownell's Firearms Manufacturing company on January 12, 2016 in Grinnell, Iowa. Bush continues his quest to become the Republican presidential nominee. (Photo by Joe Raedle/Getty Images)
WAUKESHA, WI - NOVEMBER 09: Wisconsin Governor Scott Walker (R) sits with Republican presidential candidate Jeb Bush (L) at La Casa de Esperanza during a campaign stop on November 9, 2015 in Waukesha, Wisconsin. Tomorrow Bush will participate in the third Republican presidential debate sponsored by Fox Business News and the Wall Street Journal at the Milwaukee Theater in nearby Milwaukee. (Photo by Scott Olson/Getty Images)
TAMPA, FL - NOVEMBER 2: Republican presidential candidate and former Florida governor Jeb Bush allows a supporter to loosen his necktie during a rally on his 'Jeb Can Fix It' Tour on November 2, 2015 at the Tampa Garden Club in Tampa, Florida. Following dropping poll numbers and poor debate performance Bush is trying to reset his campaign that many say has been flailing. (Photo by Brian Blanco/Getty Images)
DES MOINES, IA - AUGUST 14: Republican presidential hopeful and former Florida Gov. Jeb Bush (R) and Iowa Gov. Terry Branstad eat a pork chop on a stick at the Iowa Pork Tent during the Iowa State Fair on August 14, 2015 in Des Moines, Iowa. Presidential candidates are addressing attendees at the Iowa State Fair on the Des Moines Register Presidential Soapbox stage. The State Fair runs through August 23. (Photo by Justin Sullivan/Getty Images)
DES MOINES, IA - AUGUST 14: Republican presidential hopeful and former Florida Gov. Jeb Bush (C) talks with members of the media as U.S. Sen. Chuck Grassley (L) (R-IA) and U.S. Sen. Joni Ernst (R) (R-IA) look on during the Iowa State Fair on August 14, 2015 in Des Moines, Iowa. Presidential candidates are addressing attendees at the Iowa State Fair on the Des Moines Register Presidential Soapbox stage. The State Fair runs through August 23. (Photo by Justin Sullivan/Getty Images)
MIAMI, FL - JUNE 15: Former Florida Governor Jeb Bush waves on stage as he announces his candidacy for the Republican presidential nomination during an event at Miami-Dade College - Kendall Campus on June 15 , 2015 in Miami, Florida. Bush joins a list of Republican candidates to announce their plans on running against the Democrats for the White House. (Photo by Joe Raedle/Getty Images)
MYRTLE BEACH, SC - MARCH 18: Former Florida Governor and potential Republican presidential candidate Jeb Bush kisses a supporter during an early morning GOP breakfast event on March 18, 2015 in Myrtle Beach, South Carolina. Bush announced in December that he 'actively explore' a presidential run in 2016. He is currently on a two day tour through South Carolina and will attend several fundraising events. (Photo by Richard Ellis/Getty Images)
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In making his announcement, Graham also said that a Bush rival, Florida Senator Marco Rubio, was, at 44, too young to be president. Rubio delivered a strong performance Thursday night at a debate of the top seven Republican candidates, an event that front-runner Donald Trump was seen as winning.
Graham, 60, said he believed Rubio would be president some day, but not following the Nov. 8 election.
Pointing to his own experience, he said at age 44: "I was not ready to be president."
Stung by a series of ads against him from the Bush campaign and the SuperPAC that supports Bush, Rubio released a TV ad on Friday, calling Bush desperate.
Bush waved off the attacks, suggesting Rubio has been too sensitive in the hypercompetitive political world.
"If you're a candidate, you can't play the role of victim, and he shouldn't either," Bush said.
Graham said Trump's proposed ban on Muslims entering the United States would complicate efforts to gain support from governments in the Middle East. At the debate, Bush had said Trump's idea was flawed and that a Muslim alliance was vital.
Graham, who has been a sharp Trump critic, said Bush's bid to woo Latino voters was also critical in widening the reach of the Republican Party, which has not won the presidency since Bush's brother, George W. Bush, was reelected in 2004.
Bush, said Graham, "wants to expand a party that desperately needs to grow."
Trump dismissed Graham's move on Twitter.
"Sen. Lindsey Graham embarrassed himself with his failed run for President and now further embarrasses himself with endorsement of Bush," he tweeted.