The GOP establishment's favorite super PAC raised almost $5.2 million last month and had more than $6.3 million in the bank as of March 31, according to the report summary. That cash will be used as the outside group tries to help Republicans pick up the six seats they need to win control of the Senate. American Crossroads has been running ads supporting establishment GOP candidates in Alaska and North Carolina and is expected to support former Massachusetts Sen. Scott Brown in his bid to unseat Democrat Jeanne Shaheen in New Hampshire.

 

"There's been a noticeable rise in enthusiasm among our donors," American Crossroads chief Steven Law said, crediting candidates challenging Democratic incumbents.

 

"These numbers put us in a solid position to continue impacting key Senate races where we can help elect Republicans who will clean up the mess that President Obama and Harry Reid are making in Washington," Law said in a statement.

 

The uptick in donations could signal establishment-minded Republicans are returning to Crossroads after a disappointing 2012 and a very quiet 2013. Crossroads spent heavily on races in 2012 and came up short; 11 of the 13 Senate races where Crossroads spent money were won by Democrats, and GOP presidential nominee Mitt Romney failed to defeat President Barack Obama.

 

In all, American Crossroads spent more than $116 million between Jan 1, 2011, and Dec. 31, 2012. The group accepts unlimited donations.

 

Fundraising slowed in 2013, as is often the case in non-election years. Donors gave American Crossroads almost $1.9 million during the first six months of 2013, and just $1.7 million in the six months that followed.

 

This year, the group raised less than $52,000 in January and $257,000 in February.

 

But as donors are eyeing a map that gives Republicans a shot at returning to majority status for the first time since 2006, they are opening up their wallets.

 

Part of it could be GOP donors are remembering missteps that cost them seats in 2012. Ultra-conservative candidates won the Republican nominations in Missouri and Indiana, and Democrats went on to win Senate seats in those two states after the GOP candidates made comments about rape and abortion that Democrats harshly criticized and few Republicans defended.

 

This time, Crossroads has stepped in with ads to help favored, establishment-minded candidates prevail in primaries.

 

For instance, former Secretary of State Condoleezza Rice narrates one American Crossroads ad in support of Alaska contender Dan Sullivan, a former State Department and National Security Council official running for the Senate.

 

In North Carolina, the super PAC is running ads to help state House Speaker Thom Tillis, who is facing a raft of more socially conservative candidates who have pulled in allies from other outside groups.

 

In all, the super PAC spent $600,000 in March when it started to expand its map as more primaries were getting underway and November inches closer.

 

At the height of its spending during the final days of the 2012 campaign, American Crossroads spent $42 million between Oct. 18, 2012, and Nov. 26, 2012.

 

American Crossroads got its start under veteran GOP strategists Rove and Ed Gillespie, who is now running for Senate in Virginia. Its leaders now include Law, a former executive at the U.S. Chamber of Commerce, and Carl Forti, a former adviser to Mitt Romney and Capitol Hill Republicans.

 

The group recently hired former National Republican Congressional Committee top spokesman Paul Lindsay to run its communications shop. Former Republican National Committee chairman Mike Duncan and former RNC co-chair Jo Ann Davidson also are advisers.