As the December deadline to withdraw U.S. troops from Iraq approaches, President Barack Obama is navigating competing pressures from military officials who support keeping American troops in the country and ambivalent Iraqi officials.

Obama has sworn to abide by the agreement, negotiated under President George W. Bush, that mandates a full withdrawal by Dec. 31, 2011. But the still-tenuous security situation in Iraq has led military officials and some senators to urge more flexibility, even as Iraqi leaders weigh the benefits of bolstering security with more troops against the possibility of a violent popular backlash. The war also remains highly unpopular in America.

On Tuesday, U.S. Defense Secretary Leon E. Panetta endorsed a plan to keep 3,000 to 4,000 troops in the country. That is a smaller figure than the 8,500 or 10,000 troops the White House has proposed to Iraqi officials, according to The Associated Press, or the 14,000 to 18,000 advocated by the senior American commander in Iraq, Gen. Lloyd J. Austin III. Any decision to renege on the timetable would require explicit approval by Iraqi officials, and Prime Minister Nuri Kamal al-Maliki has said he is open to the possibility.

I think our public position, our private position, hasn't changed, that our plan is to withdraw by the end of the year, State Department spokeswoman Victoria Nuland told The New York Times. Were the Iraqi government to come forward and make a request for some continued security assistance, we would be prepared to look at it.

Some lawmakers view even 3,000 troops as inadequate. Senators John McCain, R-Ari., Joseph Lieberman, I-Conn. and Lindsey Graham, R-S.C. reacted to reports of Pannetta's plan by writing they were deeply troubled.

This is dramatically lower than what our military leaders have consistently told us over the course of repeated visits to Iraq that they require, and that is needed to support Iraq in safeguarding the hard-won gains that our two nations have achieved at such great cost, the senators wrote in a statement.

The different plans reflect in part varying assessments of the security situation in Iraq. August was the first month since the 2003 invasion that not a single U.S. soldier died, an accomplishment that officials attributed to the success of Iraqi security forces in aggressively rooting out Shiite militias.

Whatever course Obama chooses, a small army of diplomatic officials and and private security contractors will remain in the country for the foreseeable future.