The Obama administration is postponing any decision on sending more troops to Afghanistan until it's satisfied that the new government there is a "true partner".
America's top military commander in Afghanistan, General Stanley McChrystal, has asked for 40,000 more troops.
White House chief of staff Rahm Emanuel has told CNN, however, that it would be "reckless" to take such a decision without a thorough analysis of the new government.
His comments were echoed by Senator John Kerry, who said that it would be entirely irresponsible to commit more troops "when we don't even have an election finished".
Run-off election looking more likely
An investigation into fraud claims over the recent election is expected to conclude in the next few days that incumbent President Hamid Karzai did not get more than the 50% of votes he needed to avoid a second-round runoff.
Mr Karzai insists that he won the 20 August vote but EU observers say that as many as one in four votes cast was suspect.
US Secretary of State Hillary Clinton has been pressing Mr Karzai to accept that he might have to face a run-off.