With military progress scarce and doubts remaining about the reliability of Afghan President Hamid Karzai, confidence in the Obama administration's strategy in Afghanistan is deteriorating on Capitol Hill, including among prominent lawmakers who had been firm backers of the plan.

Concerns are rising as lawmakers consider a bill for $37 billion in emergency war funding for Afghanistan and Iraq. Although Congress overall still supports the U.S. mission and is unlikely to cut off funding, members may seek to attach conditions, such as requiring the administration to outline goals and fixed timetables to reduce the U.S. commitment in Afghanistan. Democratic and Republican leaders alike have said the lack of specific goals in the Obama plan makes it impossible to define success.

Obama launched a lengthy review of the war after taking office last year. He chose to increase troop strength to about 100,000 and implement a counterinsurgency strategy to try to stem gains by the Taliban militants, but he pledged that U.S. troops would start pulling out next summer. The effort has been beset by disputes with Karzai over election irregularities and systemic corruption, increasing casualties and halting progress in high-profile military campaigns.