WASHINGTON (AP) — In an indication the GOP establishment may be starting to coalesce behind him, major contributors to a key Republican political organization founded by political strategist Karl Rove have boosted their financial support for front-runner Mitt Romney.

Wealthy donors like Bob Perry, Philip H. Geier Jr. and Jerry Perenchio collectively provided much of the $6.4 million in contributions last month to the pro-Romney "super" political action committee Restore Our Future, mostly from Perry's $3 million contribution, according to campaign records submitted Tuesday to the Federal Election Commission.

The donors also are among the most generous contributors to American Crossroads, the super PAC founded by Rove, who was a top adviser to President George W. Bush. Crossroads is likely to become the pre-eminent Republican group airing negative advertisements against President Barack Obama this year.

Meanwhile, Romney's super PAC rivals have struggled to keep pace financially, their cash flows at times dependent upon longtime friends or insular donors. The Rick Santorum-leaning Red, White and Blue Fund brought in $2.9 million last month, but at least $600,000 came from close supporter and Wyoming businessman Foster Friess. For the Newt Gingrich-supportive Winning Our Future PAC, nearly 88 percent of its $5.7 million February haul came from Las Vegas couple Sheldon and Miriam Adelson.

The new campaign reports illustrate the financial advantage that Romney — the winner in Tuesday's Illinois primary — harnessed heading into Super Tuesday primary elections early this month. Romney is ahead in the count of Republican delegates and was aided by more than $29 million worth of ads paid for by Restore Our Future.

That $29 million figure is higher than spending by any other Republican super PAC or campaign, including Romney's own campaign, which raised nearly $12 million last month but burned through that by month's end. The super PAC is also aided by business interests, including more than $150,000 in donations last month from a bloc of payday-lending companies.

All told, the money flowing to Republican super PACs is expected to counterbalance cash flowing to Obama's campaign, which has raised more than $120 million in total contributions as of Feb. 29. (The PAC supporting Obama, Priorities USA Action, collected only $2 million last month.)

Super PACs are not permitted under federal law to coordinate directly with campaigns, but the PACs often pay for media campaigns that allow candidates to concentrate on state organizations and get-out-the vote efforts. Such an effort for Restore Our Future requires big cash from wealthy financiers, who last month were newcomers, repeat donors or more generous with their checkbooks. Four of note:

—Perry, 79, previously gave $1 million to the pro-Romney super PAC in addition to his $3 million last month. He also gave $2.5 million to the Crossroads group. He heads a major Houston-based homebuilding empire and has been a million-dollar player among GOP fundraisers since the late 1990s, working closely with candidates and causes tied to Rove. Perry was a big money contributor to Bush's campaigns for Texas governor and was a top bundler for his 2000 presidential race.

In 2004, Perry was the largest single donor to the Swift Boat Vets and POWs for Truth, giving nearly $5 million to the tax-exempt organization. The group, composed of Vietnam War-era Navy veterans, was blamed for misleading attacks on Democratic presidential nominee John Kerry's service as a Swift Boat officer in Vietnam. Perry also gave $3 million that cycle to the Progress for America Voter Fund, another group supporting Bush.

When Texas Gov. Rick Perry — he is no relation to Bob Perry — entered the Republican presidential race in 2011 against Romney, Perry at first supported his home state candidate, giving $100,000 to a super PAC supporting the Texan's candidacy. But as Rick Perry's campaign faltered, Bob Perry shifted his allegiance to Romney.

—Geier, 77, a veteran advertising man, gave $100,000 to the pro-Romney group after previously donating $250,000 as well as giving $500,000 to Crossroads. He is chairman emeritus of the New York-headquartered Geier Group, a global media company. Geier was a campaign bundler for Sen. John McCain's 2000 presidential campaign and has given to the Republican National Committee, as well as to GOP leaders like Sen. Mitch McConnell of Kentucky and Sen. Marco Rubio of Florida.

—Perenchio, 81, gave $500,000 and has donated $3 million to Rove's group since 2010. He is a former chairman for the Spanish-language Univision television network. He was a top bundler for McCain's 2008 presidential campaign. Perenchio, who heads Chartwell Partners LLC, gave $10,000 last year to the National Republican Congressional Committee and $5,000 to the re-election campaign of House Speaker John Boehner.

—Harold Simmons, 80, gave $100,000 following an earlier $100,000 donation in January. He also gave $100,000 last month to Winning Our Future, the super PAC supporting Gingrich; his wife, Annette, gave $1 million to the Red, White and Blue Fund. A billionaire, Simmons was the top benefactor for Rove's group, providing $12 million between his personal checkbook and the coffers of Texas-based Contran Corp., a holding company with interests including chemicals and waste management.

Simmons rivaled Perry as a $4 million contributor to the Swift Boat group in 2004 and was a bundler for the Bush and McCain presidential campaigns. In addition to his $12 million donation to Rove's group, Simmons has also given more than $200,000 to GOP candidates and party PACS and groups.

All told, super PACs have provided essential support for many campaigns. Gingrich, the former House speaker and winner of the South Carolina and Georgia primaries, collected only $2.6 million last month while spending roughly $2.8 million during the same period, his campaign said. Santorum's own campaign pulled in about $8.9 million in contributions during the same period, when he saw a surge in support.