Updated at 7:41 p.m.

Mitt Romney’s campaign raised $6.5 million for the Republican presidential primary in January, yet again winning the fundraising battle but doing it by a much smaller margin than he has previously.

The total bested the amounts raised Newt Gingrich, who pulled in $5.6 million, and by Rep. Ron Paul (R-Texas) and former Pennsylvania senator Rick Santorum, who both raised $4.5 million.

The former Massachusetts governor’s fundraising pace was also slightly slower than it was in the fourth quarter, when his campaign raised more than $24.3 million.

The Romney campaign spent heavily on the four states holding contests in January — nearly $19 million for the month — and ended it with $7.7 million in the bank. In other words, for every dollar he raised, he spent nearly $3.

At the same time, Romney still entered February in much better shape than his competition, having more money in the bank than all of his opponents combined — a reflection of his long-running fundraising dominance. All three of the other candidates had between $1.5 million and $1.8 million cash on hand, and Gingrich had nearly as much debt ($1.7 million) as cash ($1.8 million).

The top super PAC supporting Romney, Restore Our Future, narrowly outraised his campaign, bringing in $6.6 million. The two combined to spend for than $32 million for the month.

Santorum, meanwhile, raised $4.5 million for the month, which included his delayed victory in the Iowa caucuses. It should be noted, though, that he didn’t really pick up steam elsewhere in the country until this month.

Santorum, who didn’t even raised $1 million in any quarter in 2011, had $1.5 million cash on hand as of Feb. 1.

Meanwhile, Paul continues to raise money at a strong clip in the 2012 presidential race, matching Santorum’s total for the month.

The fundraising number shows the Texas congressman increased his fundraising pace slightly as the actual contests began. Paul raised $13.3 million in the fourth quarter, which was second-best clip in the GOP presidential race behind Romney.

Paul’s campaign said it had $1.6 million cash on hand at the end of January and also noted that it raised $1.7 million from a “money bomb” event last week — a number that will be included on its February monthly report.

Paul’s ability to sustain his fundraising operation is crucial, as his campaign hopes to stay in the race for months to come in an effort to accumulate as many delegates as possible.

Other top fundraising numbers that have been released include:

* Restore Our Future spent $14 million and $16.3 million cash on hand. The super PAC has been the best-funded super PAC in politics this cycle, and it spent heavily in January hoping to close out the GOP presidential race. Romney won two of four contests in January and another one in Nevada on Feb. 4 before three losses on Feb. 7 set him back.

* The top super PAC backing Gingrich raised just less than $11 million — including $10 million from Sheldon and Miriam Adelson. It spent $9.8 million and had $2.4 million cash on hand.

* Paul’s top super PAC, Endorse Liberty, raised $2.4 million and spent basically everything it had, leaving it with $60,000 cash on hand. But news broke today that Paypal founder Peter Thiel would plug another $1.7 million into the PAC.

* Former Utah governor Jon Huntsman ended his campaign owing vendors and staff more than $2.5 million — a pretty amazing amount of debt, even for a self-funder like Huntsman. Huntsman, who also loaned his campaign about $2.5 million and hasn’t repaid himself, is worth between $16 million and $71 million. A Huntsman source says $1 million of the vendor debt has been paid since the end of January, with most of it coming from Huntsman’s own pocket.

* On the other end of the spectrum, Rick Perry ended his campaign with $860,000 in the bank and no debt. He has asked whether he can use that money to form a super PAC.

* President Obama’s campaign last week disclosed that it raised $11.9 million for its campaign and another $17.3 million for the Democratic National Committee in January. Obama’s campaign committee had $75.9 million cash on hand.

* The Democratic National Committee outraised the Republican National Committee, $13.3 million to $10.5 million. The two are on pretty similar financial footing, with the RNC having $23.4 million cash on hand and $11.8 million in debt and the DNC having $15.7 million cash on hand and $6 million in debt.

Campaigns must file their January fundraising numbers by midnight tonight.