Mr. Warner, a Virginia Republican who is one of the most important Congressional voices on military policy, said mounting numbers of dead and wounded Americans, the contentious process of drafting an Iraqi constitution and the economic cost of the war were adding up to new anxiety in Congress.
"The level of concern is, I think, gradually rising," Mr. Warner said in an interview on Friday. "Our nation has given so much to the Iraqi people, and what are they giving us in return?"