The Democratic independent group House Majority PAC and the labor giant SEIU are teaming up to spend $20 million on congressional races this fall, a strategist familiar with the plans confirms to POLITICO.

The two groups have reserved airtime in several dozen congressional races, with House Majority PAC shouldering about 80 percent of the cost.

I reported recently on the partnerships cropping up between Democratic-leaning groups to fight the GOP's financial superiority, and this is a prime example of that trend. SEIU has also teamed up with the pro-Obama super PAC Priorities USA Action to run ads courting Latino voters for the president.

House Majority PAC clocked a significant win recently when it helped Democrats retain control of Arizona's 8th Congressional District, the seat of former Rep. Gabrielle Giffords.