WASHINGTON - US Senator John Kerry Wednesday said it was "common sense" for President Barack Obama to wait until after Afghanistan's run-off election before making fateful decisions on deploying more US troops.

Kerry, fresh from his Afghan mediating mission, emerged from Oval Office talks with Obama saying far-reaching decisions on deploying tens of thousands more US troops should await results of the November 7 election.

"I think that as a matter of common sense, the president would feel that it makes sense to wait until the end of this two-week period," Kerry told reporters outside the White House.

"Two weeks is a very short span of time to determine whether you have a government to work with in a war.

"It is very hard for me to think the president will decide otherwise."

Kerry said he could not see how US parents could be asked to send their children off to fight a war "that requires good government and you don't know what the government is."

The senator's comments came hours after White House spokesman Robert Gibbs said it was "possible" the president would deliver his long-awaited judgement on sending more troops to Afghanistan before the second round of voting.

"I know when the election is, I don't know when the decision is going to be, so it's certainly possible," Gibbs said, when asked whether the troop decision could come before the second election.

Obama invited Kerry to the White House hours after he returned from Afghanistan, where he played a key role in convincing President Hamid Karzai to enter the run-off polls, following August's corruption-tainted initial vote.

An inquiry by a UN-backed watchdog this week into the August 20 election, confirmed staggering levels of fraud, most of it in favor of Karzai. It declared more than one million ballots suspect -- almost a quarter of the total cast.

Karzai had long argued that he won a clear first-round majority and that claims of widespread fraud were fabricated.