Peter Overby

Former Massachusetts Gov. Mitt Romney's six primary wins on Super Tuesday didn't come cheap. An NPR analysis shows that last week alone, the Romney campaign and the pro-Romney superPAC combined spent nearly $7 million on TV ads.

Less than $1 million of that was spent by Romney's official campaign, while the pro-Romney superPAC Restore Our Future — which has almost exclusively engaged in negative advertising this year — spent $5.7 million.

That's compared to $220,000 spent on ads last week by the superPAC supporting former Pennsylvania Sen. Rick Santorum.

It's Super Tuesday for the Republican presidential contenders, and 10 states are holding primaries and caucuses.

Former Massachusetts Gov. Mitt Romney hopes he can firm up his front-runner status — a status that, an NPR analysis shows, has so far involved his campaign and a pro-Romney superPAC burying the opposition with negative messages.

The financial battle for the Republican nomination is tightening. Candidates spent a lot of cash in January — what with contests in Iowa, New Hampshire, South Carolina and Florida. Also spending a lot of money, as it turns out, were the richly financed superPACS that support the candidates.

Reports filed at the Federal Election Commission on Monday night show just how important a superPAC can be.

President Obama's decision to have White House officials and Cabinet secretaries help raise money for a pro-Obama superPAC is raising questions.

The superPAC, Priorities USA Action — which is supposed to be independent of the president's re-election campaign — is launching a new effort to bring in six- and seven-figure contributions.

By law, it cannot coordinate its messaging with Obama's re-election campaign committee. But coordinating other things? That's possible.

As the Republican candidates were rallying their supporters in Florida on Tuesday night, their campaigns were quietly sending disclosure reports to the Federal Election Commission in Washington. The big picture: Mitt Romney had more money than Newt Gingrich. President Obama had more than either of them. And a few of the new superPACs filed donor lists filled with high rollers.

Tuesday's disclosures run only through Dec. 31 but still reveal some essential truths.

In the race for the Republican presidential nomination, former House Speaker Newt Gingrich continues to fend off accusations that he should wear the scarlet "L" — for "lobbyist." This week, he released two of his consulting contracts and said they didn't call for any lobbying.

Like many other former lawmakers, Gingrich was advocating for paying clients, while not officially registering as a lobbyist.

The two contracts disclosed this week came from Gingrich's work for Freddie Mac, the mortgage giant. Between 1999 and 2007, Freddie Mac paid his firm $1.6 million.

The South Carolina primary is a week from Saturday. Before then, voters there can expect to be inundated with ads attacking Republican presidential candidate Mitt Romney and his role in Bain Capital.

"We made a $3.4 million ad buy in South Carolina, which is fairly significant," says Rick Tyler, senior adviser to the pro-Newt Gingrich SuperPAC Winning Our Future.

"Fairly significant" hardly does justice to the SuperPAC's plan.

This is the season of the presidential super PACs: They flooded Iowa with attack ads and now they are looking ahead to primaries in South Carolina and Florida.

Super PACs (political action committees) can solicit big, corporate contributions — something candidates can't do. And, according to the law, super PACs are barred from coordinating their ads with the candidates they support. But it's not nearly that simple.

A Super PAC Attacks