Washington: A debate is intensifying inside the White House over whether President George W. Bush should try to prevent more Republican defections by announcing intentions for a gradual withdrawal of troops from high-casualty Iraqi areas, the New York Times said on Monday.

Citing administration officials and consultants, the newspaper said these officials fear the last pillars of political support among US Senate Republicans for Bush's Iraq strategy are "collapsing around them."

The president and his aides had thought they could wait to begin discussions about any change in strategy after September 15, when the US commander in Iraq, General David Petraeus, and US ambassador to Iraq, Ryan Crocker, must present a much-anticipated report on Iraq's security and political progress.

But these aides acknowledge it appears that forces are converging against Bush just as the Senate prepares this week to begin what promises to be a contentious debate on the war's future and financing, the newspaper said.

On Sunday, Defense Secretary Robert Gates canceled a long-planned trip to Latin America to help prepare a report for the US Congress on the war, according to the Pentagon.

The administration must deliver an interim report to Congress by July 15 on Iraq. The report has gained significance as an increasing number of both Republican and Democratic lawmakers call for a change in Bush's strategy in Iraq.

Four more Republican senators, including Pete Domenici of New Mexico last week, have recently declared they can no longer support the strategy.

The Times said Gates has been quietly pressing for halving the number of brigades patrolling the most violent sections of Baghdad and surrounding provinces by early next year.

The remaining combat units would take up the more limited mission of training Iraqi units, protecting Iraq's borders and taking on Al Qaida in Mesopotamia, the Sunni extremist group affiliated with Osama Bin Laden.