Updated

A pair of "super" political action committees supporting top Republican presidential candidates spent nearly $24 million in January, drawing upon major gifts and repeat donations from wealthy business executives, according to financial reports the groups filed Monday with the government.

The super PACs -- Mitt Romney-leaning Restore Our Future and Newt Gingrich-supportive Winning Our Future -- raised a combined $17 million last month. That financial strength allowed the groups to hit the airwaves in key primary states with millions of dollars in expensive TV ads.

The groups' fundraising offers a periodic behind-the-scenes glimpse into the identities of the wealthy supporters who will help elect the next president, along with details on how the tens of millions of dollars they donated have been spent this election season. Restore Our Future, which spent $14 million last month, has been boosted by more than two dozen repeat donors. Winning Our Future, which spent $9.7 million, is largely supported by casino mogul Sheldon Adelson and his wife.

The super PACs, as well as other groups supporting other candidates and the individual campaigns, were required to disclose how much they raised and the identities of their donors in reports filed with the Federal Election Commission by midnight Monday.

Those reports provided a snapshot of fundraising for President Barack Obama's early campaign and for Republican candidates as they battled during important primary elections in January. During the month, GOP candidates Newt Gingrich and Rick Santorum had briefly surged ahead of front-runner Mitt Romney but trailed the former Massachusetts governor in fundraising. Since then, Santorum has climbed remarkably in polls as support eroded just as stunningly for Gingrich following his disappointing showing in Florida.

Restore Our Future has been a boon for Romney, who has benefited greatly from the group's TV ads attacking Gingrich in particular. Such ads were purchased thanks to the financial help of repeat donors, including Marriott International Chairman J.W. Marriott Jr., who has given the super PAC $750,000 to date.

The super PAC also reported new donors, including Hewlett-Packard CEO Meg Whitman. Romney mentored Whitman, recently an unsuccessful candidate for California governor, during the 1980s at Boston-based Bain & Co., the private equity firm Romney headed. Whitman's $100,000 check to Restore Our Future came days after she joined Romney at a celebration of his victory in the New Hampshire primary.

Restore Our Future counted on continued support from at least 30 repeat donors who have given a combined $6.6 million in January, according to a review of the reports by The Associated Press.

Meanwhile, Winning Our Future's $11 million in contributions during the same period came almost exclusively from Adelson, a friend of Gingrich's and a staunch supporter of Israel. Adelson and his wife, Miriam, each gave $5 million to the super PAC in January -- a move that helped keep Gingrich's struggling campaign alive.

Other GOP-leaning super PACs reported major contributions.

Endorse Liberty, the group supporting Texas Rep. Ron Paul, reported roughly $2.4 million in donations, including $1.7 from the billionaire founder of PayPal, Peter Thiel of San Francisco. Thiel, who runs a hedge fund, is a libertarian who has supported Republican causes and candidates and also has donated to California's marijuana legalization ballot measure.

Obama's campaign last Friday reported raising a combined $29.1 million in January among the campaign, the Democratic National Committee and other joint fundraising committees. The major super PAC backing Obama, Priorities USA Action, has yet to file its January report.

Romney raised $6.5 million last month for his presidential bid, while Gingrich's presidential campaign raised $5.5 million last month.

The reports likely will rekindle criticism of the groups, which were made possible under a 2010 Supreme Court ruling in the Citizens United case. The super PACs must legally remain independent from the candidates they support, but many are staffed with former campaign aides who have intimate knowledge of the campaigns' strategies.

Late Friday, the Supreme Court put on hold a Montana case that bore striking similarities. Two justices said the newest case provides an opportunity for the court to reconsider whether the millions of dollars that millionaires and billionaires have poured into the presidential election should be allowed to continue.