American Crossroads has upped its fundraising game, bringing in $5.2 million in March after a slow start to the election cycle.

The GOP-aligned group, run by Karl Rove, was the main force on the right during the 2012 campaign, but hasn't raised and spent much since then.

The big month shows the organization is reengaging ahead of the 2014 elections. It raised just $300,000 in January and February, but the organization's ability to raise unlimited funds means it can ratchet up in a hurry.

The big month coincides with increased efforts from the group. It's airing ads in North Carolina touting GOP establishment favorite Thom Tillis in his race against Sen. Kay HaganKay Ruthven Hagan2020 Dems compete for top campaign operatives Senate GOP rejects Trump’s call to go big on gun legislation Politics is purple in North Carolina MORE (D-N.C.) as well as in Alaska, defending Dan Sullivan's (R) Senate campaign against attacks.

The group has mostly taken a back seat on the right to Americans for Prosperity, the group backed by billionaires Charles and David Koch that has spent more than $30 million in the 2014 election cycle. American Crossroads also has raised less than the Senate Majority PAC, the Democrats' main Senate super-PAC, which brought in $11 million in the first quarter and has $8.5 million in the bank.

But the big month shows the pro-establishment GOP group may be shifting into higher gear.