The race for Iraq's new prime minister has tightened after one of two top Shi'ite candidates dropped out of the contest.

The party representing Interim Finance Minister Adel Abdul-Mahdi says it withdrew his name Tuesday to preserve unity in the United Iraqi Alliance. The Shi'ite group won 48 percent of the vote in last month's election for a national assembly.

This leaves Ibrahim al-Jaafari, a former London-based opposition figure, as the likely new front-runner. Mr. al-Jaafari told the Associated Press Tuesday that if he becomes the new prime minister, he would not push for a U.S. withdrawal from Iraq any time soon.

Meanwhile, the U.S. military says an American soldier was killed in action Tuesday in the restive Anbar province, west of Baghdad.