Meantime, a new Pew Research Center analysis finds that Obama's early job approval ratings are already the most polarized of any president in the past four decades.
"Republicans who were somewhat disposed to Obama in January and early February have moved away from him in pretty substantial numbers," says Andrew Kohut, who directs the nonpartisan Pew Center.
Third, Obama's policies are less popular than he is, polls show.
Rep. Chris Van Hollen of Maryland, who chairs the House Democratic campaign committee, says the fate of congressional Democrats and Obama "are very closely tied together."
But with joblessness expected to run high for many months, the economy could hurt Democrats who must face voters next year, when Obama won't be on the ballot. Increasingly, Democrats in Congress may see their choice coming down to either backing Obama's ambitious and expensive agenda or saving their own necks.
"A lot of what we saw in 2008 was an Obama phenomenon," says Steve Jarding, a Democratic campaign strategist. "The Democratic Party has to be very careful, because they're living a little bit on a false pretense that somehow this Obama phenomenon reaches beyond Obama. You can't just live on those coattails."
Democrats can't rely, either, on Republicans continuing to struggle for a message or a leader. "I remember the headlines when Jimmy Carter got elected," about the Republicans being dead, he says. "Four years later, we had the Reagan revolution."
