The U.S. Senate on Tuesday endorsed a March 31, 2008, target date for withdrawing American combat troops from Iraq, moving Congress a step closer to a showdown with President George W. Bush over the war. By a vote of 50-48, the Senate defeated an amendment that would have stricken the withdrawal language from a $121.6 billion bill that mostly would fund the wars in Iraq and Afghanistan. A final vote on the bill is expected later this week. ~ snip ~