Billionaires B. Wayne Hughes, Paul Singer and Ken Griffin are among two dozen donors who together gave $5.2 million last month to American Crossroads, a Republican group aligned with political strategist Karl Rove.

Hughes, co-founder of Public Storage, sent $500,000 to American Crossroads, federal records show. Singer, founder of New York-based investment firm Elliott Management Corp., and Griffin, chief executive officer of Chicago-based Citadel Advisors LLC, each gave $250,000.

American Crossroads, a super-political action committee that can accept donations in unlimited amounts, disclosed its donors late yesterday to the Federal Election Commission in Washington after announcing its fundraising totals last week.

“There’s been a noticeable rise in enthusiasm among our donors, in part due to the impressive slate of candidates who are strengthening the opportunity to win a Republican majority in the Senate,” American Crossroads Chief Executive Officer Steven Law said in a statement.

Democrats control 55 of the 100 U.S. Senate seats and are the defending party in 21 of the 36 races this November, including seven in states that President Barack Obama lost to Republican Mitt Romney in the 2012 election. American Crossroads has aired television advertisements in three of those states -- Alaska, Montana and North Carolina.

American Crossroads also helped Florida Republican David Jolly win a special U.S. House election last month in a district that voted for Obama in 2012.

Biggest Check

The PAC’s biggest donation last month was a $2 million check from Jerry Perenchio, a former chairman of New York-based Univision Communications Inc. It got $100,000 from Linda McMahon, a co-founder of World Wrestling Entertainment Inc. who lost races for a Connecticut Senate seat in 2010 and 2012.

American Crossroads raised more than $9.1 million for the 2014 campaign through March, FEC reports show. It took in more than $117 million for the 2012 election.

Super-PACs, which grew out of a series of court rulings and regulatory decisions in 2010, mostly spend money on independent ads aiding or opposing candidates. They can’t coordinate with political campaigns.