What could go wrong?

“We need to get out the message that it’s now really dangerous to re-empower the Republican Party,” said one Democratic strategist who has spoken with White House advisers but requested anonymity to discuss private strategy talks.

Democrats are divided. The party’s House and Senate campaign committees are resistant, not wanting to do anything that smacks of nationalizing the midterm elections when high unemployment and the drop in Mr. Obama’s popularity have made the climate so hostile to Democrats. Endangered Congressional candidates want any available money to go to their localized campaigns.

Late Sunday night, White House advisers denied that a national ad campaign was being planned. “There’s been no discussion of such a thing at the White House” or the Democratic National Committee, said David Axelrod, Mr. Obama’s senior adviser.