In a news conference Wednesday, Richard Trumka, the A.F.L.-C.I.O.’s president, said that without the huge push by the nation’s labor unions, Mr. Obama never would have won Ohio, Wisconsin and Nevada — and their combined 34 electoral votes. In his news conference, Mr. Trumka stopped short of saying he expected any quid pro quo from Mr. Obama. But he made clear what organized labor hoped for, especially as the White House prepares to negotiate with Republicans on Capitol Hill on how to reduce the budget deficit.