Members of an independent commission on Iraq policy could not reach a consensus Tuesday on how many or how long U.S. troops should remain in Iraq, forcing the group to return for a third day of debate, according to an official close to the panel's negotiations.

Panel members mostly made no comment as they left the Woodrow Wilson Center on Tuesday afternoon. But Leon Panetta, former White House chief of staff to President Clinton , hinted at some struggles, telling reporters, "Trying, trying to find a ... trying to find consensus. ... It goes up and down."

The Iraq Study Group , a bipartisan panel created to recommend changes in U.S. war policy, is having difficulties reaching agreement on what the appropriate level of U.S. troops should be in Iraq, whether there should be a phased withdrawal, and if so, under what time frame, said the official, who spoke on condition of anonymity because the panel's deliberations are private.

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A second official has said that the commission was unlikely to propose a timetable for withdrawing U.S. troops from Iraq but that some members seemed to favor setting a date for only an initial withdrawal, an idea that has been pushed by many congressional Democrats.

The first official said Tuesday that the group was still struggling over whether to set a hard deadline for withdrawing U.S. forces or if there should be any short-term increase in troops as the U.S. works to train and build up Iraq's security forces. There are currently about 139,000 U.S. troops in Iraq.

The questions are key to the U.S. future policy in Iraq following the November election in which Democrats swept control of the House and Senate largely due to voters discontent with the progress of the war.

Leaving the daylong meeting Tuesday afternoon, members of the panel, which is headed by former Republican Secretary of State James A. Baker III and former Democratic Rep. Lee Hamilton, played down any divisions among the diverse group.

"It's a good group to work with, let's just put it that way," said Panetta, as he emerged with Vernon Jordan, who was a Clinton adviser, and former Republican Sen. Alan Simpson of Wyoming.

The group was initially expected to wrap up their deliberations Tuesday. People close to the commission said they expect the panel to issue a bipartisan, consensus report some time next month.

Officials have said a consensus report is the group's goal, rather than having the panel issue one that suggests two divergent opinions with no clear recommended path.

Panel members are also expected to urge the Bush administration to reach out to Iran and Syria, as part of an effort to get regional governments involved in stabilizing Iraq.

Bush, attending a NATO summit in Riga, Latvia, renewed his pledge Tuesday not to pull U.S. troops out "until the mission is complete." He also repeated a warning to both Iran and Syria not to meddle in Iraq.

Complete coverage is available in FOXNews.com's Iraq Center.