WASHINGTON – President Barack Obama’s top commander in Afghanistan has told him that without more troops the United States could lose the war that Obama has described as the nation’s foremost military priority.

Obama must now decide whether to commit thousands of additional American forces or try to hold the line against the Taliban with the troops and strategy he has already approved. Obama made clear in television interviews Sunday that he is reassessing whether his narrowed focus on countering the Afghan insurgency is working and will not be rushed into a decision about additional troops.

“Resources will not win this war, but under-resourcing could lose it,” Gen. Stanley McChrystal wrote in a five-page summary of the war as he found it upon taking command this summer.

Obama approved 21,000 additional U.S. troops earlier this year, on the advice of Gates and other senior defense and military leaders. That will bring the number of U.S. troops in Afghanistan to a record 68,000 by the end of this year, working alongside 38,000 NATO-led troops.

The question now is whether to divert troops from Iraq or make other adjustments to expand that force significantly early next year. Gates and others have repeatedly warned that too large a force would do more harm than good in a country hostile to anything it sees as foreign meddling. But Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, told Congress last week he thinks more troops are probably necessary.

The Pentagon and the White House are awaiting a separate, more detailed request for additional troops and resources. Media reports Friday and Saturday said McChrystal has finished it but was told to pocket it, partly because of the charged politics surrounding the decision. McChrystal’s senior spokesman, Rear Adm. Gregory Smith, told The Associated Press on Sunday the report is not complete.

“The way forward in Afghanistan … is complex,” Pentagon spokesman Bryan Whitman said. “There are political aspects, developmental aspects, economic, a range of things you have to look at.”

In Congress, the war has taken on a highly partisan edge. Senate Republicans are demanding more forces to turn around a war that soon will enter its ninth year, while Democrats are trying to put on the brakes.