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Pro-Romney super PAC makes big ad buys in South Carolina, Florida

Republican presidential frontrunner Mitt Romney tells TODAY's Matt Lauer that the "relatively modest heat" coming from his GOP rivals is a "good warm-up" for the general election.

A super PAC backing Mitt Romney has just made nearly $6 million in new ad buys in South Carolina and Florida in an apparent attempt to blow away the GOP frontrunner's opponents by the end of the month.

A source close to Restore Our Future, the pro-Romney super PAC, confirmed that in the last few days it has bought up $2.3 million of media time in South Carolina and another $3.6 million in Florida to run ads in those states.

Read more reporting from Michael Isikoff in 'The Isikoff Files'

These buys show the powerful financial muscle behind the Romney group - flush with big donations from wealthy Wall Street investors and others. They also exceed the reported $3.4 million ad buy that Winning Our Future, the pro-Gingrich super PAC, made in South Carolina this week after receiving a $5 million infusion from billionaire casino magnate Sheldon Adelson.

In his victory speech after winning the New Hampshire primary, Mitt Romney criticizes President Obama and contrasts his agenda with characterizations of Obama's time in office.

The clash of the rival super PACs that can take unlimited donations from wealthy contributors and corporations - is increasingingly dominating the GOP presidential race. A firm that tracks media buys for NBC News has found that, even before these buys, the Romey super PAC had already spent $7 million on ads in the primaries, exceeding the $5.5 million that was spent by the official Romney presidential campaign.

The super PAC ads are also far more nasty than those being run by the campaigns. In his victory speech tonight, Mitt Romney took a pointed shot at other Republicans who he said were "dividing" the country - a clear shot at blistering ads that the Gingrich super PAC has vowed to run attacking Romney for costing thousands of workers their jobs when he ran the private equity firm Bain Capital.

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NBC’s Chuck Todd explains how the outcome of New Hampshire’s primary plays into the plans and strategies of the Republican competitors, particularly with regard to preventing Mitt Romney from becoming the nominee.

Rick Tyler, a spokesman for the Gingrich super PAC, said that Romney should stop "whining" about his group's ads - and said they will begin running on South Carolina TV and radio stations by Thursday morning.

"It’s amazing that he would take the opportunity of his victory speech to allow us to get under his skin," Tyler said.