(CBS News) Former New York Mayor Rudy Giuliani on Monday officially endorsed Mitt Romney for president, calling him "the most effective Republican."
While two other Republicans -- Newt Gingrich and Ron Paul -- are still in the primary contest, Giuliani said on Fox News that Romney has "won fair and square."
"He's taken on everybody and won an incredible number of primaries, and he's got the resume and the background for the job," he said. "This is going to be an election about the economy, and if I look at all the Republican field and Democratic field, who better than Mitt Romney to carry our banner and to point out this has been a failed economic program and that [with] sensible, conservative economic principles, this country will have a boom."
The former mayor, himself a 2008 candidate for the Republican nomination, played down the significance of one of Romney's biggest shortcomings against President Obama: the likability factor.
The latestshowed that while just 42 percent of registered voters view Mr. Obama favorably, only 29 percent view Romney favorably. On top of that, about half of voters said Mr. Obama is , but just 34 percent said the same of Romney.
Giuliani compared the presidential race to choosing a surgeon.
"If I've got a terrible cancer or something to be operated on -- when I had to be operated on for prostate cancer - I didn't go to the nicest doctor, I went to the best doctor," he said. "The guy could have a great personality... and put the knife in the wrong way."
Giuliani added that the perception that Romney isn't likable is "overdone."
"He's a nice guy and just as personable [as the president]," he said. "I know both of them. I know Mitt better, but I know the president. both are very nice men. President Obama is not nicer than Mitt Romney or vice-versa."