"It would have been so much easier and I think much more compelling to say success on the ground can be achieved within a year to 18 months, I'm confident of that, but we're going to stay until we get the job done," the former GOP presidential candidate added.
Vice President Joe Biden on "GMA" defended the president's timeline, saying the new strategy is "narrowed and focused."
"There would be over 100,000 American troops, 135,000 NATO and allied troops in the region. How are they emboldened knowing that by the time we train up the Afghanis we're going to be gradually handing off," Biden told "GMA's" Diane Sawyer. "This idea that somehow they're [Taliban] going to lay low and all of a sudden come racing back when we only have 98,000 troops there, it's just not logical to me."
"In the meantime, if they lay low, that would be just wonderful because it would allow us to train up even faster the Afghan troops, allow us to further degrade al Qaeda in Pakistan, and allow us to further help the Pakistanis have a more capable military to take on the bad guys in the western part of their country," he added.
As for whether 30,000 additional troops will be enough, Biden said, "My view all along has been, less important the numbers than what the strategy is."
Meanwhile, some of Obama's own party members are skeptical of the surge. Today, Senate Armed Services Committee Chairman Sen. Carl Levin, D-Mich., expressed reservations about the troop increase in his opening remarks of the hearing.
"It seems to me that the large influx of U.S. combat troops will put more U.S. Marines on street corners in Afghan villages, with too few Afghan partners alongside them," he said.
Other Democrats are concerned about the costs associated with a troop surge. On Tuesday, the president, who met before his speech with Congressional leaders, said this new approach would cost $30 billion this year and that he would work with lawmakers to address that cost.
Obama delivered a sober assessment Tuesday night of the security situation in Afghanistan and announced that after a lengthy strategy review he has ordered 30,000 additional troops, which will be deployed starting in early 2010, to target insurgents and secure key areas there.
"These additional American and international troops will allow us to accelerate handing over responsibility to Afghan forces, and allow us to begin the transfer of our forces out of Afghanistan in July of 2011," the president said before a crowd of roughly 4,000, mostly West Point cadets. "Just as we have done in Iraq, we will execute this transition responsibly, taking into account conditions on the ground."
The reaction among war-weary U.S. troops on the ground in Afghanistan was mostly positive, with many weary soldiers welcoming the surge.
"The president said things that I think most of us here anticipated that he would say," U.S. Army Col. Jay D. Haden, based in Kabul, told ABC News. "I'm very supportive of it, it sounds like a solid plan. I think it's consistent with the wishes and hopes of the most of the people here."
Obama argued that the surge would accelerate the process of training Afghan national security forces, and handing over to them the responsibility sooner than later, in turn allowing U.S. troops to come home, starting in 2011.