WASHINGTON, Aug. 17 — The White House plans to use a report next month assessing progress in Iraq to outline a plan for gradual troop reductions beginning next year that would fall far short of the drawdown demanded by Congressional opponents of the war, according to administration and military officials.

One administration official made it clear that the goal of the planned announcement was to counter public pressure for a more rapid reduction and to try to win support for a plan that could keep American involvement in Iraq on “a sustainable footing” at least through the end of the Bush presidency.

The officials said the White House would portray its approach as a new strategy for Iraq, a message aimed primarily at the growing numbers of Congressional Republicans who have criticized President BushÂ’s handling of the war.

Most Congressional Democrats have already called for the withdrawal of all American combat forces from Iraq beginning early next year. “After nearly five years, a half-trillion dollars and over 3,700 American lives, it is long past time for a change of direction in Iraq,” the Senate’s Democratic majority leader, Harry Reid of Nevada, said in a written statement this week.