CHICAGO  President-elect Barack Obama put the rancor and even some of the rhetoric of the presidential campaign behind him on Monday as he welcomed his chief Democratic adversary into his cabinet and signaled flexibility in his plans to withdraw troops from Iraq.

Introducing a national security team anchored by Hillary Rodham Clinton as secretary of state, Mr. Obama said a new strategic agreement with Baghdad put the United States “on a glide path to reduce our forces in Iraq.” But while he reaffirmed his desire to pull out combat brigades within 16 months, Mr. Obama emphasized his willingness to consider options put forth by the military.

“I believe that 16 months is the right timeframe,” Mr. Obama said at a news conference, with Mrs. Clinton and Robert M. Gates, whom he is keeping on as defense secretary, as well as other appointees. “But as I have said consistently, I will listen to the recommendations of my commanders. And my No. 1 priority is making sure that our troops remain safe in this transition phase and that the Iraqi people are well served by a government that is taking on increased responsibility for its own security.”

Mr. Obama has long qualified his withdrawal pledge, but in the campaign the emphasis was on his intent to end the war. Now that he is taking office in 50 days, he is calibrating his statements to leave room to maneuver, knowing that some senior military officers are wary of moving too quickly and that the defense secretary he just reappointed has cautioned about timetables.