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Republican presidential candidate and former Massachusetts Gov. Mitt Romney speaks with the media after a visit to his campaign headquarters on January 31, 2012 in Tampa, Florida. Romney has a double-digit lead going into the Florida primary today.

TAMPA, FL -- Mitt Romney on Tuesday defended the increasingly negative tenor of the GOP primary campaign, telling reporters that he would not "stand back" as other candidates attacked him.

"It would be wonderful if campaigns were all nothing but positive, but that's certainly not the reality," Romney said at a press availability outside his headquarters here. "President Obama will have a billion dollars or so to attack me. He's already begun. The AFL-CIO I understand spent about a million dollars in Florida attacking me. So there are going to be attacks, and the right thing to do will be to respond to them aggressively, clear up those things that have been said that are incorrect, and point out the weaknesses-- the differences between yourself and those that you're running against."

Romney also defended his own negative attack ads and rhetoric targeting former House Speaker Newt Gingrich with the political equivalent of the playground "he started it."

"You know, in South Carolina, we were vastly outspent with negative ads attacking me and we stood back and spoke about President Obama and suffered the consequence of that and also some good debates by speaker Gingrich. We came to Florida and Speaker Gingrich didn’t have two good debates. I did. and we responded to the attacks that were coming to us," Romney said.

That would seem to be a bizarre claim at first glance, given the Romney campaign's status as the richest of all the candidates. The campaign has spent millions throughout the campaign, as has Restore OUr Future, a pro-Romney super PAC. NBC News and ad-tracking firm Smart Media Group Delta, which tracks ad spending by political candidates, reported that Romney and Restore our Future outspent Gingrich and his Super PAC by more than $2 million dollars in South Carolina.

The Romney campaign explained the governor meant they were outspent versus all the other candidates' combined spending.

"I’ll tell you if you’re attacked I’m not going to just sit back I’m going to fight back and fight back hard. I did note that in the Suffolk University poll they asked the people in Florida who has run the most negative campaign in Florida and they said Newt Gingrich," Romney said, referencing a poll which showed 37% of Floridians felt Gingrich ran the most negative campaign, compared to Romney's 31 percent. "He really can’t whine about negative campaigning when he launched a very negative campaign in South Carolina and when the people here in Florida looked at the different campaigns and concluded his was the most negative."

Romney certainly has fought back -- over the airwaves, on the stump and with his surrogates.

Romney's campaign and Restore our Future outspent Gingrich and his allied Super PAC Winning our Future on advertising by nearly a 4-1 margin here, with team Romney spending $15.9 million to team Gingrich's $4 million. Romney also spent the better part of the last two days opening every campaign event by attacking Gingrich, and several of his congressional endorsers have shadowed the former speaker's campaign events, where they've occasionally clashed with Gingrich staffers in what Romney advisers refer to as a "truth squad" operation.

With a spate of recent polls showing Romney expected to coast to victory here tonight, he conceded today he will soon need to pivot his focus back to President Obama, but also left no doubt he'd be keeping up the pressure on Gingrich going forward.

"I would like to spend more of our time focusing on President Obama. That's ultimately what's going to be essential to taking back the White House," Romney said. "But I'm not going to stand back and allow another candidate to define me. [Gingrich's] comments most recently attacking me have been really quite sad and I think painfully revealing about the speaker and what he's willing to say and do to try to take the nomination. So I just can't stand back and let him say those things about me without responding."