McCain received a big boost last night when Republican Gov. Charlie Crist, who is extremely popular among GOP voters in Florida, endorsed him.

McCain not only refused to apologize to Romney yesterday, but at his next campaign appearance McCain lashed out at his rival, saying: "The apology is owed to the young men and women serving this nation in uniform, that we will not let them down in hard times or good. That is who the apology is owed to."

His campaign then issued a statement in which McCain said that Romney may have changed his mind on the idea of a buildup of troops in Iraq but that "the fact is, like on so many other issues, Governor Romney has hedged, equivocated, ducked and reversed himself."

Asked why he was bringing up Romney's quotes nearly a year after he made them, McCain replied, "I've been criticizing him for months." He added that it makes sense to highlight them in Florida, noting: "I'm in a state that has enormous military involvement. I'm trying to convince them that I'm best qualified to be commander in chief."

McCain's support for the surge of troops in Iraq nearly doomed his campaign early last year, but his decision to stand by it helped revive his White House bid when fortunes in Iraq improved. The leading GOP candidates have all sought to emphasize their support for the Iraq war as polls show that a large majority of Republicans support it.

McCain's emphasis on Iraq also returns the focus of the campaign to foreign policy and the military, issues that the longtime senator and military hero believe play into his strengths. Voters have said they are most concerned about the economy, a strong point for Romney, who made millions as a businessman.

The dislike between the candidates was evident on Friday, when McCain's campaign released an online-only ad featuring Romney's face superimposed on the figure of Sen. John F. Kerry (D-Mass.) windsurfing -- an ad from the 2004 presidential campaign that caricatured Kerry as an inveterate flip-flopper.

In the ad, titled "Mittsurfing," an announcer asks: "Which way does Mitt Romney stand? Whichever way the wind blows."