Sept. 27 (Bloomberg) -- Two top Republican senators urged President Barack Obama to send as many as 40,000 additional troops to Afghanistan to prevent the Taliban and al-Qaeda from gaining the upper hand there.

“I’m very hopeful that the president will make the right decision, which is to commit the necessary troops,” Senator John McCain, the senior Republican on the Armed Services Committee, said today on ABC’s “This Week.” “A half-measure does not do justice. And time is important, because there’s 68,000 Americans already there and casualties will go up.”

Another member of the committee, Senator Lindsey Graham of South Carolina, said the U.S. risks losing the fight without sufficient forces in place.

“We will be driven out. The Taliban will come back stronger than they were before. The moderates in Afghanistan will go back in hiding or get killed. NATO will be seen as a failure,” he said on CBS’s “Face the Nation”.

Obama, who ordered 17,000 additional combat troops sent to Afghanistan earlier this year, is reviewing U.S. strategy in the conflict. The Washington Post reported last week that the top U.S. commander in the country, General Stanley McChrystal, submitted a classified assessment that 10,000 to 40,000 more troops would be needed to carry out a counterinsurgency mission.

Weighing Options

Obama said on Sept. 16 that he won’t be making a decision until all the options are explored and discussed with his advisers and military officials. Defense Secretary Robert Gates said today on ABC’s “This Week” that the he hasn’t given the McChrystal report to Obama.

“I’m going to sit on it until I think -- or the president thinks -- it’s appropriate to bring that into the discussion of the national security principles,” he said.

The U.S. casualty rate has climbed in recent months and polls show public support for the war is declining. Some Democrats in Congress, led by Senator John Kerry of Massachusetts, have been expressing doubts about the war effort.

Senator Christopher Bond warned Obama against “dithering” over a decision on strategy. The Missouri Republican said on “Fox News Sunday” that “the next nine to 12 months will be decisive.”

Democratic Senator Dianne Feinstein of California said on the same program that Obama is right “to take his time, to really examine what the alternatives are at this time.”

The Afghanistan strategy hasn’t worked well so far, she said, adding that the American public doesn’t want to be militarily engaged in Afghanistan for another decade.

To contact the reporters on this story: Daniel Whitten in Washington at dwhitten2@bloomberg.net.

Last Updated: September 27, 2009 13:52 EDT