MIAMI, Florida (CNN) -- Former New York Mayor Rudy Giuliani ended his GOP presidential race and endorsed rival Sen. John McCain of Arizona on Wednesday.
Ex-New York Mayor Rudy Giuliani, with wife Judith, speaks of his campaign in the past tense in Orlando.
And sources say California Gov. Arnold Schwarzenegger might endorse McCain on Thursday.
"This is a man who is prepared to be president," Giuliani said of his "old friend."
Giuliani said McCain gives the Republican Party the best chance to hold onto the presidency.
"I am very proud to endorse my friend and fellow Republican -- a hero -- John McCain," Giuliani said at the Ronald Reagan Presidential Library in Simi Valley California, two hours before the Republican presidential candidates were to face each other in their final debate before the Super Tuesday contests next week.
Meanwhile, two Republican sources told CNN that California Gov. Arnold Schwarzenegger is in discussions about endorsing McCain.
One of the sources said, "you can safely describe the conversations as progressing and productive." The second source described the endorsement as "more than expected" and said the conversations were aimed at arranging a Thursday announcement.
Giuliani described McCain as "the other best candidate."
"I made it clear before I had to make this decision [to drop out] that had I not run, I'd be supporting John McCain," Giuliani told reporters on a flight to Burbank, California, for the debate.
The debate is being sponsored by CNN, the Los Angeles Times and Politico, and begins at 8 p.m. ET.
Giuliani, who had staked his presidential campaign on a Florida win, had a disappointing third-place finish in the state's Republican primary Tuesday night.
He largely skipped the early voting states to put all his energy into Florida.
"Obviously, the strategy didn't work," he said. "We're going to go back and try to find out why. I don't have the answers ... Having said that, it was the only strategy available to us -- could we have done it in a better way? I don't think we know the answer to that right now."
His endorsement of McCain, who won in Florida, gives the Arizona senator added momentum heading into Super Tuesday, when more than 20 states hold contests.
McCain's Florida win essentially turns the GOP presidential race into a two-man contest between him and former Massachusetts Gov. Mitt Romney.
McCain finished 5 percentage points ahead of Romney, 36-31. Giuliani placed a distant third with 15 percent of the vote, followed closely by former Arkansas Gov. Mike Huckabee, who held 14 percent.
The win gives McCain all 57 Florida delegates at stake.
The victory also is significant because it proves McCain can win a contest solely involving Republicans. Florida is a closed primary, so no crossover voting among Republicans and Democrats is allowed.
McCain's primary wins in New Hampshire and South Carolina were due in part to the backing of independents who cast ballots in the GOP contests. Read how CNN's analysts view Tuesday's results »
However, McCain still finished second to Romney and Huckabee with conservatives and evangelicals, two key wings of the Republican Party.
Huckabee campaigned in Florida and also has spent time stumping in some Southern states that will vote on Super Tuesday.
But Huckabee's campaign lacks the resources to match McCain and Romney, and his failure to win the South Carolina primary set back the former Baptist minister's White House bid.
Rep. Ron Paul of Texas also is concentrating on the February 5 states, but he is well behind McCain and Romney in the polls. Watch how McCain has emerged as the GOP front-runner »
"Our victory might not have reached landslide proportions, but it is sweet nonetheless," McCain told supporters at a Miami rally. "My friends, in one week we will have as close to a national primary as we've ever had in this country. I intend to win it and be the nominee of our party." Hear excerpts from McCain's speech »
But McCain, who cultivates an image as a maverick, must work to convince the GOP's conservative base to back him. Many conservatives vilify the senator for breaking with them on immigration, campaign finance, taxes and other issues.
"People are trying to find a reason to vote for McCain. I have talked to any number of people in the last 24 hours that are shaking their heads saying, 'You know, I just won't vote,' " said conservative radio talk-show host Rick Roberts on Wednesday. "If McCain ends up being the nominee, I predict the lowest voter turnout for Republicans in my memory."
Since Friday, McCain and Romney and their camps have fired away at each other over the Iraq war, the economy, illegal immigration and border security, campaign finance reform and the environment -- each accusing the other of pursuing "liberal" policies.
A senior Romney aide said Tuesday night the candidate's camp viewed the contest as one between a Washington insider and an outsider and will argue that Romney represents change while McCain is "more of the same."
In the following week, Romney is expected to rally conservatives.
He took aim at McCain on Tuesday night, putting his opponent on the hot seat for failures in Washington, his criticisms of President Bush and his move directly from the military into Congress.
"Washington is fundamentally broken," Romney said. "We're not going to change Washington just by sending the same people back just to sit in different chairs."
On the Democratic side, Tuesday's vote in Florida may have little impact on the presidential race because the party's national leadership said it would not allow the state's delegates to participate in the national convention after a squabble over scheduling the primary. The party's candidates agreed not to campaign actively in Florida
Republicans penalized the state as well but took away only half of their 114 delegates.
With about 99 percent of Democratic precincts reporting, Sen. Hillary Clinton of New York had 50 percent of the vote. Sen. Barack Obama of Illinois placed second with 33 percent, and former Sen. John Edwards of North Carolina was in third with 14 percent.
With no delegates at stake, Clinton nonetheless claimed victory, thanking her supporters. She has called on the Democratic Party to lift sanctions on the state.
"I promise you I will do everything I can to make sure not only are Florida's Democratic delegates seated, but Florida is in the winning column for the Democrats in 2008," Clinton told supporters Tuesday night. E-mail to a friend
CNN's Gloria Borger, John King, Alexander Mooney, Bill Schneider and Paul Steinhauser contributed to this report.
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