WASHINGTON — The top commander in Afghanistan said this morning that the United States will need a substantial military presence in the country in 2013 despite the increasing clamor for an accelerated American drawdown after more than a decade of war.

“My opinion is that we will need significant combat power in 2013,” Marine Gen. John Allen told the Senate Armed Services Committee.

Pressed by the panel’s top Republican, John McCain, on whether a force of 68,000 would be sufficient, Allen said, “Sixty-eight thousand is a good going-in number, but I owe the president some analysis on that.”

President Barack Obama faces increasing political and public pressure to accelerate the timetable after more than a decade of war and recent incidents that dealt a major setback to the fragile U.S.-Afghanistan relationship, including Afghan outrage over the burnings of Qurans and a shooting spree that left 17 Afghan civilians dead. Those two events have been blamed on Americans.

Allen said the United States is on track to reduce the 23,000-member surge force by the end of September, but he said he won’t make his recommendation on the pace of further reductions until the last three months of the year — an announcement likely to come after Election Day.