TAMPA, Fla. - Just hours before he learns the results of the Florida primary, Mitt Romney says when it comes to negative campaigning, "When attacked, you have to respond."

I asked the former governor about the campaign ads that have aired in Florida over the past week, 92 percent of which were negative in tone, according to Kantar Media's Campaign Media Analysis Group.

Romney and his allies vastly outspent Gingrich, according to a source with information on ad spending in the state. Romney and his super PAC spent $12 million in Florida - or more than four times what Gingrich and his allies spent.

"In South Carolina, we were vastly outspent by negative ads against me and stood back and talked about President Obama," Romney responded. "Plus, there were good debates from Speaker Gingrich. We came to Florida, Speaker Gingrich didn't have good debates and I did."

Romney added, "If you're attacked, I'm not going to just sit back, I'm going to fight back and fight back hard."

Romney said he was outspent on negative ads in South Carolina, but he spent far more than his opponents on ads of all kinds. According to sources tracking spending in the Republican primary, the Romney campaign alone spent more than double the Gingrich campaign on TV advertising. Romney did not begin running negative television ads against Gingrich until after his South Carolina loss, but the super PAC supporting him, was spending the vast majority of its money on negative attacks.

Read more about primary ad spending in South Carolina and Florida.

When asked how important a role Florida is playing in the nomination process, Romney responded, "Today, Florida is the most important thing in the world to me."