"I'm looking at changing the mission," he said. "I truly have thought about this very long and hard. I think we have a war on terror, that is how we began in 2002, that's what we should go back. Staying there and to trying to build a nation that does not have an economy, does not have an infrastructure, and by all accounts have a corrupt government. How long would we have to be there and how many troops would it take in order to be successful?"
the president will announce the U.S. will pull 10,000 troops out of Afghanistan by the end of this year and that all 33,000 surge troops will be out by September 2012.
Manchin also made the economic argument against continuing the war in light of huge federal deficits.
"It's coming down to a choice, can you afford Afghanistan at the present rate that we're doing, we've spent 443 billion dollars, we're on track to spend another 485 billion dollars ... So here we are and are trying to build a nation that by all accounts that doesn't maybe doesn't want to be rebuilt," he said.
"It's time to rebuild our country. We're gonna get ourselves to a position that we can't even help ourselves, let alone help the people in need around the world," Manchin added.
During a Senate debate on troop levels in Afghanistan on Tuesday, Sen. John McCain, R-Ariz., had a heated exchange with Manchin over his position on the war.
McCain called Manchin's comments "uniformed about history and strategy."
In the interview Wednesday, Manchin said he has the "utmost respect" for McCain and "the sacrifices he's made to our country."
"He's absolutely correct - I don't have the experience he's had," Manchin said. "But what I do have, like a lot of West Virginians, is a little bit of common sense and enough is enough."
In aon Wednesday, McCain defended continuing the war in Afghanistan, but he disagreed with Mr. Obama's withdrawal plan. He said the administration was taking "unnecessary risk" and that it was "unfortunate" Mr. Obama would go against "well-known recommendations" of military leaders.
Watch more of the interviews with McCain and Manchin below: