Things always change in politics, but that would defy history. And even senior Obama strategists acknowledge that they feel more confident about states where his approval rating reaches 47 percent or above. That's the same number transfixing many Republicans. "It's very difficult for a president to get reelected if their job approval is less than 47 percent in a two-way race," GOP pollster Whit Ayres said at a National Journal conference this week.

It's not beyond Obama to hit that mark (some polls already put him there). But he's not guaranteed to get (or stay) there, either. The glum conclusion inside the White House is that the economy isn't likely to provide him much of a tailwind before Election Day. The smaller-scale administrative initiatives he's now consistently announcing may help only at the margin.

Obama's team is most optimistic about improving his ratings through the comparison with the eventual Republican nominee. That debate, they hope, will remind people of first-term accomplishments like the auto-industry rescue and shift attention toward ideas such as reducing the deficit through a mix of spending cuts and upper-income tax increases, which consistently outpolls the GOP's cuts-only approach. Put another way, they hope that clarifying the choice will help them win the referendum. Of course, Republicans will use that same debate to remind voters about the aspects of Obama's term they like least--such as his stimulus failing to dent high unemployment.

Unless Obama can rebuild his approval rating above 50 percent, which seems unlikely without faster economic growth, he'll win reelection only by convincing several million voters currently disappointed in him that they would like the Republican alternative even less. That points toward a bruising year.

Obama strategists say that no matter whom the GOP nominates, the president will deliver the same core message: A Republican president would rubber-stamp the agenda of the GOP Congress and return to policies that caused the crash, favor the wealthy, and squeeze the middle class. Against any Republican, Obama appears determined to stress the populist notes he's amplified lately about economic inequality.

But the GOP alternatives will provide very different contexts for those arguments. Obama's team hasn't thought much about a matchup against Herman Cain--which appears even less necessary now with him floundering in a sexual-harassment controversy. Texas Gov. Rick Perry, they believe, might be a stronger competitor than Mitt Romney for blue-collar whites and Latinos but ease Obama's recovery with economically discontented white-collar whites who still generally prefer that their president believe in evolution. The former Massachusetts governor offers the inverse equation: Although his boardroom background may play well in white-collar suburbs, it could alienate blue-collar whites if Obama can portray him as embodying cutthroat corporate greed.