WASHINGTON — President Bush yesterday rejected the advice of some aides that he should announce a pullback of troops in Iraq, even though the White House confirms that Baghdad’s government has made little political progress.

“Troop levels will be decided by our commanders on the ground, and not by political figures in Washington, D.C.,” he said, dismissing calls from several Republican senators that he should abandon the “surge” of troops mainly around Baghdad.

Mr. Bush was speaking days before an interim report on the progress of the surge was due to be presented to Congress. White House officials said the report would be gloomy because Prime Minister al-Maliki’s government had failed to meet any of the security and political benchmarks Mr. Bush set for it in January.

In recent weeks, Senators Lugar, Voinovich, and Domenici — Republicans formerly loyal on Iraq — had indicated they had run out of patience. More than 60% of Americans believe that America should withdraw some or all of its troops.

But Mr. Bush, whose popularity rating is now dipping below 30%, said in a speech in Cleveland, Ohio: “The killers who came to America have said, with clarity, we want you out of Iraq so we can have a safe haven from which to attack again. What would the Iranians think about America if we stepped back in the face of this extremist challenge? What would other extremists think? What would Al Qaeda be able to do? They’d be able to recruit betterand raise more money. Failure in Iraq would have serious consequences for the security of your children and your grandchildren.”

Although some White House aides had briefed that Mr. Bush would speak about his “vision for the post-surge” and that this week’s interim report, rather than the fuller report due in September, marked a decision point, Mr. Bush insisted it was far too early to reach any conclusions.

General David Petraeus, commander of American forces in Iraq, and Ryan Crocker, the U.S. ambassador to Iraq, are due to testify to Congress around September 15.

Mr. Bush said: “It’s in this nation’s interests to give the commander a chance to fully implement his operations, and I believe Congress ought to wait for General Petraeus to come back and give his assessment of the strategy that he’s putting in place before they make any decisions.”

Republicans remain deeply divided over Iraq with an increasing number feeling defeat is inevitable. Democrats are united in opposition, with presidential candidates adopting increasingly strident troops-out stances.

In a speech in Iowa yesterday, Senator Obama, a Democratic presidential candidate, said: “Our message to the president is clear. It is time to begin ending this war — not next year, not next month — but today.” His rival, Senator Clinton, is working on an amendment to repeal congressional authorization for the war.

Senator McCain, a Republican candidate, speaking fresh from a visit to Iraq, gave Mr. Bush some much-needed support, saying, “The progress our military has made should encourage us.”

The surge strategy was “the correct one” and had to be given time to work. He added that it was certain that if Congress were to “legislateanendtothisstrategyjustas it is beginning then we will fail.” The failure of the Iraqi government to reach its targets, however, creates a political headache for Mr. Bush. Frederick Kagan of the American Enterprise Institute think tank, one of the architects of the surge, said the use of benchmarks had been a mistake.

But he said there were “some very early signs of political progress” and the troops needed for the full surge had been in place less than a week.