WASHINGTON — Fundraising has tumbled for several leading Republican super PACs as the 2014 election season heats up.

Three groups affiliated with Republican strategist Karl Rove — American Crossroads, Crossroads GPS and the Conservative Victory Project — took in $6.1 million in 2013. That's a sharp drop from 2012 when American Crossroads alone raised $99.1 million as it sought, unsuccessfully, to put the White House and Senate in Republican hands.

Crossroads spokesman Jonathan Collegio said the group would have the money to compete in November's elections. Republicans control the House and need to pick up six seats to win the majority in the Senate. Collegio said fundraising pledges are on track with earlier election cycles.

The Congressional Leadership Fund, a separate Republican super PAC focused on House races, reported taking in slightly more than $1 million last year — a fraction of the nearly $11.2 million it raised in 2012. In addition, a rival Democratic group, the House Majority PAC, raised about $7.5 million last year.

Democrats would need a net gain of 17 seats to take control of the House, and most independent analysts expect the chamber to remain in Republican hands.

Fundraising always slows in a non-election year. But some GOP strategists say they are worried that their party's donors have become too complacent.

"There is a perception among Republican donors that our House majority is not at stake," said Charlie Spies, who is affiliated with several GOP super PACs. "The reality is that if Democrats continue to raise significantly more money, that overwhelming advantage could create issues for Republicans in November."

Contributing: Christopher Schnaars