WASHINGTON—Two Karl Rove-backed Republican campaign groups raised more than $325 million during the 2012 election cycle, a draft tax return shows, a record haul for an outside political group that for the first time eclipses the fundraising efforts of a national political party.

That total means American Crossroads and its nonprofit sibling, Crossroads GPS, together outraised the Democratic National Committee, which took in $316 million during the 2012 cycle, according to the Center for Responsive Politics, a nonpartisan group that tracks campaign spending.