FireDogLake speculates that Pres. Obama plans to link Congressional races to his reelection campaign. As a general rule, that is always a stupid idea.
Presidents like to nationalize their reelections. Nixon did it; Clinton did it. The idea is to present a unified theme where all campaigns are subsidiary to the President's. The result is that local Congressional candidates can't run effective campaigns as the head of the ticket sucks off all of the attention and the cash. The principal benefit is that it strokes the inflated ego of the President and enrich the President's campaign staff.
It's theoretically possible for a President to altruistically help Congressional campaigns in states the President himself can't possibly win. It's possible for President to step back and allow Congressional candidates to take the lead in their own districts. It's possible. I've just never seen it.