Tampa, Florida (CNN) - Mitt Romney said he's learned his lesson from a stinging loss in South Carolina.
"If you're attacked, I'm not going to just sit back," he told reporters in Tampa on Tuesday, repeating a refrain he's used regularly recently. "I'm going to fight back and fight back hard."
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He immediately hammered that lesson home, unleashing a string of harsh attacks on his rival Newt Gingrich. He accused the former House speaker of whining and of making attacks on Romney that were "painfully revealing" and "really quite sad."
The press conference capped off 10 days in Florida in which Romney dropped the above-the-fray approach he had used throughout the campaign, and instead repeatedly jabbed Gingrich himself.
But while Romney chalked up his South Carolina loss to being "vastly out-spent" on attack ads, he ignored the fact that Gingrich was the candidate out-spent in that state's primary.
The Republican candidate said Tuesday he believed independent voters would not be turned off by the bruising GOP primary, saying many voters are determined to see a new president in office.
"It would be wonderful if campaigns were all nothing but positive, but that's certainly not the reality," Romney said, pointing to a billion dollars he said President Barack Obama was prepared to use against him.
Romney was also asked at his press conference to outline his plan to turn around the housing market.
The GOP candidate declined to offer many specifics, but said he would "get the economy going," get people back to work and avoid what he called a mistake by Obama.
"Don't do what President Obama did, which is to stop the process of foreclosure," he said, adding state attorneys general should prosecute those committing fraud. "But the idea of trying to stop the foreclosure process kept it from occurring, kept the market from bottoming and recovering. You have to let the market work and let home values recover as a result of that."