Baghdad, Iraq - The U.S. military is weighing new directions for Iraq, including an even bigger troop buildup if President Bush thinks his "surge" strategy needs a further boost, the chairman of the Joint Chiefs of Staff said Monday.

Marine Gen. Peter Pace revealed that he and the chiefs of the Army, Marine Corps, Navy and Air Force are developing their own assessment of the situation in Iraq, to be presented to Bush in September. That will be separate from the highly anticipated report to Congress that month by Gen. David Petraeus, the top commander for Iraq.

The Joint Chiefs are considering a range of actions, including another troop buildup, Pace said without making any predictions. He called it prudent planning to enable the services to be ready for Bush's decision.

The military must "be prepared for whatever it's going to look like two months from now," Pace said in an interview while traveling to Iraq from Washington.

"That way, if we need to plus up or come down" in numbers of troops in Iraq, the details will have been studied, he said.

Pace said another option under consideration is maintaining current troop levels beyond September.

There are now about 158,000 U.S. troops in Iraq, reflecting a boost of about 30,000 to carry out the new strategy Bush announced in January. The plan is focused on providing better security for Iraqis in Baghdad, but the intended effect - political reconciliation between Sunnis and Shiites - has yet to be achieved, and many in Congress are clamoring to begin withdrawing troops soon.

In Washington on Monday, Senate Democratic leader Harry Reid said he would force the chamber's first all-night debate on the Iraq war tonight in advance of a vote Wednesday on whether to bring home all combat troops by next spring.

Republicans are using Senate rules to insist that the measure have 60 votes to pass - a de facto filibuster since it takes that many votes to cut off debate.

The rare, round-the-clock session is intended to bait Republicans into an exhaustive debate on the politically unpopular war, as well as punish GOP members for routinely blocking anti-war legislation.

"How many sleepless nights have our soldiers and their families had?" said Democratic Whip Dick Durbin, D-Ill.

Democrats are trying to ratchet up pressure on Republicans who have grown uneasy with the lack of progress and begun questioning Bush's strategy.

Republicans shrugged off the planned marathon debate as political theater. Minority Leader Mitch McConnell, R-Ky., said Republicans "welcome further debate" but that there was no reason why the Senate couldn't vote sooner.

The political sparring came as several Republican congressional staffers met privately with Bush aides in the West Wing of the White House to hash out an effective communications strategy on the war.

According to one staffer, Bush made a brief surprise visit and thanked them - spokespeople for Republican leadership on Capitol Hill - for sticking behind him.

Bush told the staffers he would not rethink his Iraq policies until the critical military assessment comes in September.