But the challenge in Afghanistan is becoming more difficult in the face of gains by the Taliban, rising U.S. casualties, a weak Afghan government widely viewed as corrupt, and a sense among U.S. commanders that they must start the military effort largely from scratch nearly eight years after it began.
A turnaround is crucial because military strategists believe they will not be able to get the additional troops they feel they need in coming months if they fail to show that their new approach is working, U.S. officials and advisors say.
"Over the next 12 to 15 months, among the things you absolutely, positively have to do is persuade a skeptical American public that this can work, that you have a plan and a strategy that is feasible," said Stephen Biddle, a military expert who advises the U.S.-led command in Afghanistan.
A similarly urgent view was voiced by military and diplomatic officials who described the administration's goals and self-imposed deadline during recent interviews in Afghanistan and Washington. Most spoke on condition of anonymity because they are not authorized to comment publicly.
Defense Secretary Robert M. Gates, in an interview last month, first pointed publicly to the need for progress by next year. Since then, the goal has spanned the administration's international diplomatic efforts, its aid program for the Afghan government and its combat strategy.
Unlike during the Bush administration years, when Defense Secretary Donald H. Rumsfeld clashed with other Cabinet members, particularly in the State Department, Gates' assessment appears to be shared by every other major Obama administration player. At the White House, State Department and elsewhere, officials agreed on the need for rapid progress in key areas.
Besides reversing Taliban advances and strengthening the central government, U.S. officials will strive to hold the NATO alliance intact while reshuffling deployments to consolidate gains, especially in the eastern part of the country, near the Pakistani border.
Administration goals in Afghanistan also include stemming government corruption, improving security forces, especially the police, and reducing violence through efforts such as wooing insurgents.
In part, the administration thinking reflects the growing impatience of liberal Democrats with the war. Sen. Russell Feingold of Wisconsin has called for a "flexible timetable" for troop withdrawals, while House Appropriations Committee Chairman David Obey of Wisconsin has warned of funding cuts next spring unless there is significant progress.
A senior administration official said Obey's comment was "a very important signal" to the White House.
Among military commanders, there has been no effort to sugarcoat conditions in Afghanistan.
"We need a fundamental new approach," said one officer, a senior advisor to Army Gen. Stanley A. McChrystal, the newly appointed top commander in Afghanistan.
McChrystal's initial assessment of Afghanistan to Pentagon officials is due soon, in a report expected to be made public in early September.
That report will probably avoid a troop recommendation, but by outlining McChrystal's view of what has gone wrong and his vision for fixing it, officers hope he can make Washington more receptive to a later request for more troops.
"We have to demonstrate we have a clear way ahead, matched with appropriate resources, that is making an impact on the ground," said the officer.
The proportion of Americans who believe it was a mistake to send troops to Afghanistan rose from about 25% in 2007 to 42% this year, according to Gallup surveys. A slight majority of Americans no longer believe the war is worth fighting, according to a Washington Post-ABC survey this month.
August has been the deadliest month for U.S. troops in Afghanistan. A U.S. fighter was killed Friday when his vehicle hit an explosive device in eastern Afghanistan, bringing the number of U.S. military deaths to 45 and exceeding the previous record, set in July. At least 732 U.S. service members have been killed in the Afghanistan war, compared with more than 4,300 killed in the Iraq conflict.
The faltering public support highlights another concern: the U.S. midterm elections next year. Democratic lawmakers fear they may become targets of Republican political attacks over the administration's handling of the war.