“The Democrats — their coalition has been around a while, and it’s tried and true, and they all know how to tango together. And the Republicans are all kind of doing their own individual dances,” said John Feehery, a Republican strategist.

Coordination on the right has been hampered by competition for donors and lingering distrust between the party-allied groups, like the Crossroads organizations, founded by Karl Rove, and those seeking to challenge the party establishment, such as Americans for Prosperity and Freedom Partners, the lead players in the political network overseen by the billionaire brothers Charles G. and David H. Koch. The two sides have jockeyed for cash and influence, while also grappling with a wave of ideologically tinged primary battles this spring and summer that sucked up time, money and good will.

To keep donors secret, most of the pro-Republican money is coursing not through super PACs but through political nonprofits. These groups do not have to disclose much about their finances, but are more restricted than super PACs in the types of advertising they can air. (In part to address the problem, the Koch network has pumped more cash into its sole super PAC, Freedom Partners Action Fund.)

While Republicans have spent more over all on advertising during the midterm campaign, their cash has been spread among a larger array of groups. Many of them are newer organizations established or expanded by the Koch network this cycle. Others sprang up to cater to donors angry at the poor performance of Crossroads and other consultant-run groups in 2012.