President George W. Bush is expected to emphasise today that his strategy in Iraq is aimed at eventually bringing US troops home, as he seeks to stem growing Republican defections from his war policy.
"Troop levels will be decided by our commanders on the ground, and not by political figures in Washington, D.C.," Bush, who was to speak about Iraq later in Cleveland, told reporters during a stop in Ohio.
With senior Republican senators calling for a shift, the White House is increasingly worried about a further erosion of Republican support.
Bush has asked for more time to allow the troop surge he ordered at the start of the year to work. A report he must deliver to Congress by July 15 on progress by Iraq's government will show mixed results and is likely to fuel debate.
President Bush is expected to stress that the troop buildup is part of an attempt to lay the groundwork for an eventual withdrawal of US forces.
"The president will continue to talk about how he believes that we should try to get to the goal that all Americans, we believe, want, and that is a stable, peaceful Iraq," White House spokesman Scott Stanzel told reporters.
Reflecting growing impatience among Republicans for change, Tennessee Senator Lamar Alexander pushed a proposal to embrace the recommendations of the Iraq Study Group calling for a shift for US troops away from a combat role and toward training and supporting Iraqi troops.
"The surge by itself in my opinion is not a strategy," Alexander told CNN.
Bush has said repeatedly that the troops will return from Iraq when security conditions warrant.
Mr Bush vehemently rejects the idea of a timetable for a troop withdrawal.
Public support for the war has plummeted and Bush's own approval ratings are at the lowest of his presidency.
A new USA Today/Gallup poll showed today that more than seven in 10 Americans favor withdrawing nearly all U.S troops from Iraq by April. Sixty-two per cent said the United States made a mistake in sending troops to Iraq, marking the first time that number has passed 60 per cent in that survey.