November 1, 2009 Abdullah drops out, effectively handing Karzai victory Play video

(NECN/ABC) - The top challenger in a presidential runoff election in Afghanistan dropped out of the race Sunday, citing concerns of fraud. The decision by Abdullah Abdullah clears the way for the incumbent President Hamid Karzai to lead the nation for another five years.

But there are continuing doubts about the legitimacy of the election. And those doubts create headaches for the White House as it struggles to draw up a new battle plan for the Afghanistan war.

The 67,000 U.S. troops, 42,000 allied troops stationed in Afghanistan and the Afghan people are all affected by Abdullah Abdullah's decision to quit next weekend's presidential runoff.

"I will not participate in the November 7th election," Abdullah said.

Abdullah's exit from the presidential race hands victory to the incumbent, President Hamid Karzai -- a victory that is tainted by massive fraud in the first election held in August.

Still, Abdullah urged his followers to remain calm.

"So that's the call for my supporters: not to get to the streets, not to go to the streets, no demonstrations," Abdullah said.

President Karzai is now set to rule the war-torn nation for another five years -- and to fight a Taliban insurgency amidst accusations that he is ineffective and corrupt.

"I think it is time for us to stop beating up on President Karzai and start building up President Karzai and his government to be the government we need, because they are not the

And that enemy is still inflicting heavy casualties.

October was the deadliest month of the eight-year war for U.S. forces.

President Obama is still considering sending up to 40,000 more troops to Afghanistan to combat the growing insurgency.

ABC's Brad Wheelis reports.