WASHINGTON — There are seven days until early voting begins in Iowa, less than two weeks until the first debate and 46 days left in the race for Mitt Romney to change the dynamic of a campaign that by many indicators is tilting against him.

That, advisers to President Obama acknowledge, is plenty of time.

But the burden rests to a remarkable degree directly on Mr. Romney and his ability to restore confidence to his campaign, become a more nimble candidate and clearly explain to voters why he would be the better choice to repair the economy and lead the nation in addressing its challenges at home and abroad.

The state-by-state landscape facing Mr. Romney is more daunting than he expected by this stage in the contest. He anticipated, aides said, to be in a position of strength in at least some of the states that turned Democratic in 2008 for the first time in a generation, but few of them show signs of breaking decisively his way, and Mr. Obama still has more and clearer paths to 270 electoral votes.

And as Mr. Romney works to move beyond one of the most turbulent periods of his candidacy, in a week dominated by the disclosure of remarks in which he said that 47 percent of Americans do not pay taxes and see themselves as victims, he is starting to confront criticism from some in his party who worry that his troubles will affect their own races.