The U.S. military is likely to keep an expanded force of about 160,000 troops in Iraq through the Dec. 15 election of a new government and then make a “fairly rapid” reduction to what has been the standard troop level of about 138,000, a senior Pentagon official said Thursday.

Marine Corps Lt. Gen. James T. Conway, the director of operations for the Joint Chiefs of Staff, told a Pentagon news conference that there currently are “just short of” 160,000 American troops in Iraq.

Conway also confirmed a Los Angeles Times report that the Pentagon is considering putting a general with more seniority in charge of a task force that has been struggling for two years to defeat the main weapon Iraqi insurgents are using to kill and maim American troops: the improved explosive device, or homemade bomb.

U.S. commanders have raised troop levels in advance of Iraqi elections because of expectations that the insurgents would intensify their attacks in an effort to stop the voting.