McCain: Obama could make 'error of historic proportions' on Afghanistan

Sen. John McCainJohn McCainTrump should apologize to heroic POWs McCain urges sports leagues to return 'paid patriotism' money Senators to Obama: Make 'timely' call on Afghan troops levels MORE (R-Ariz.) said that the United States cannot win the war in Afghanistan without the 40,000 additional troops that the top military commander there is said to be recommending.

McCain was asked Sunday on CNN’s "State of the Union" if American forces could prevail with a surge of fewer than 40,000 troops.

“I do not,” responded McCain, Obama’s GOP rival for the presidency in 2008.

“I think the great danger now is not an American pullout,” McCain said. “I think the great danger is a half-measure.”

President Barack ObamaBarack ObamaObama: 'Stop to reflect' on Memorial Day John Bolton slams Obama’s ‘shameful apology tour’ Miss. governor to join lawsuit against Obama transgender policy MORE is weighing the possibility of sending tens of thousands of new troops to Afghanistan upon the recommendation of Gen. Stanley McChrystal, who has prepared a troubling assessment of the eight-year-old war and determined that a much larger military force will be needed to turn the tide of the conflict.

Reports of the still-confidential McChrystal report have put the number of recommended new troops at 40,000.

While criticizing the leaking of the McChrystal report, McCain called the details that have been reported by the press “generally accurate.”

“I have urged the president to act with deliberate speed,” McCain said. “I hope the president will heed the advice of his advisers.”

McCain said that if Obama chooses to follow a course different than the one urged by his generals on the ground, he will be making “an error of historic proportions.”

Obama has not indicated how he will handle the McChrystal report other than making assurances that he intends to listen to a range of opinions regarding Afghanistan before deciding whether more troops or any new strategy is needed.

On "Meet the Press," Armed Services Committee Chairman Sen. Carl LevinCarl LevinCarl, Sander Levin rebuke Sanders for tax comments on Panama trade deal Supreme Court: Eye on the prize Congress got it wrong on unjustified corporate tax loopholes MORE (D-Mich.) said the president needs to carefully weigh the options to maximize the chance of success in Afghanistan. Levin said opined that the best way forward is to send more trainers to mold the Afghan forces, citing Iraq as the model for success.

"At this time, don't send more combat troops," Levin said. "...The surge that will really work will be a surge of Afghan troops."

Armed Services Committee member Sen. Lindsey GrahamLindsey GrahamSenators to Obama: Make 'timely' call on Afghan troops levels Senate amendments could sink email privacy compromise Trump: Romney 'walks like a penguin' MORE (R-S.C.) disagreed, saying that efforts at training will be unsuccessful without a secure ground situation.

"Without better security and more combat power we're going to lose in Afghanistan," Graham said.

Graham challenged Obama to "earn the award he was given" by implementing a "robust strategy," even offering to build Obama a cabinet to store his Nobel peace prize if the president manages to turn around the war in Afghanistan and keep Iran from obtaining nuclear weapons.

"Obama will be judged by the decision he makes" on Afghanistan, Graham said.

Graham predicted that if McChrystal's recommendations are followed, Afghanistan could be turned around in 24 months.