WASHINGTON -- President Barack Obama is weighing whether to deploy 10,000 more troops to Afghanistan but lawmakers on both sides of the aisle are questioning an increased commitment and seeking specific measures of progress against the deteriorating conditions in Afghanistan and Pakistan.

When President Obama took office, the U.S. had about 38,000 troops in Afghanistan. The White House has announced plans to send 21,000 reinforcements in coming months, increasing the tally to almost 60,000.

Mr....