The chairman of the Senate Armed Services Committee pressured President Obama on Friday to stick to his commitment to begin withdrawing troops from Afghanistan in July 2011.

Sen. Carl LevinCarl LevinPresident Trump, listen to candidate Trump and keep Volcker Rule Republicans can learn from John McCain’s heroism Trump and GOP wise to keep tax reform and infrastructure separate MORE (D-Mich.), the chairman of the influential committee, urged Obama to be inflexible on the target date he'd set to begin troop reductions.

"The president is now under pressure from inside and outside the military to build flexibility into that July 2011 date," Levin said in prepared remarks he's set to deliver to the Council on Foreign Relations. "I want to tell you why I believe sticking to that date is essential to success, and why President Obama should not, and I believe will not, modify the July 2011 date."

Levin, an opponent of the original surge of troops into Afghanistan that Obama ordered last fall, said that sticking to the date was critical to "strengthen Afghan resolve" to build its own internal military and policing systems to fend off Taliban-led insurgents once the U.S. leaves the country.

Levin also said that he'd become convinced Obama wouldn't back down on his commitment to begin withdrawing U.S. troops from Afghanistan, after almost 10 years of military involvement in that country.

"I am convinced, after talking to President Obama and to administration officials, that the president will not waffle in his decision to begin reducing our force levels by July 2011," he said. "I’m sure there will be lots of pressure to do so."

Republicans and some figures within the Obama administration have urged the president to be more flexible on the timeline. The U.S. withdrawal, they argue, should be tied to conditions on the ground, which, if they don't improve, may justify an extended U.S. presence in the region.

“You can’t win conflicts when you tell the enemy you’re leaving," said Sen. John McCainJohn Sidney McCainSenate's defense authorization would set cyber doctrine Senate Dems hold floor talk-a-thon against latest ObamaCare repeal bill Overnight Defense: Senate passes 0B defense bill | 3,000 US troops heading to Afghanistan | Two more Navy officials fired over ship collisions MORE (R-Ariz.), the ranking member of Levin's committee, in mid-September. "That worries me more than anything else.”

Levin made reference to some of the fissures that were made public in Washington Post journalist Bob Woodward's new book.

"I have tried, everywhere I could, to build resistance to the pressure to turn a date-certain into a goal, or something based on conditions rather than a commander in chief’s decision and order," Levin said. "I have done so because open-ended commitments encourage drift and permit inaction; firm timelines demand attention and force action."