Mr. Obama got a taste of that in recent days as he and his White House were put on the defensive trying to explain why the unemployment rate had risen to 9.4 percent when his staff had predicted it would peak at 8 percent as long as Congress passed his stimulus plan, which lawmakers dutifully did. Mr. Obama obviously did not create the recession passed to him, but it was his administration that set the expectation that his policy would keep it from deepening as far as it has.

Challenges stacking up overseas may increasingly be seen as Mr. Obama’s soon enough too, say advisers, critics and some outside experts. By sending an extra 21,000 American troops to Afghanistan and replacing the commander there, Mr. Obama has now made that war his, as many analysts in Washington see it. The forceful position toward Israel that Mr. Obama has adopted in recent weeks over settlement expansion may also make the Palestinian conflict more and more his own problem.

“I think they’ve got till summer” until these issues become fully vested with Mr. Obama, said Ed Gillespie, a former White House counselor to Mr. Bush. “But the novelty’s already starting to wear off.”…

“When a president tries new policies to deal with old problems and then new policies appear to be failed policies, then he owns it,” said George C. Edwards III, a presidential scholar at Texas A&M University. “That’s the challenge for a president.”