"It would be an unconscionable act of betrayal, a stain on our character as a great nation, if we were to walk away from the Iraqi people and consign them to the horrendous violence, ethnic cleansing and possibly genocide that would follow a reckless, irresponsible and premature withdrawal," McCain told the Los Angeles World Affairs Council in California.
Sens. Barack Obama, D-Ill., and Hillary Clinton, D-N.Y., have a starkly different take.
"I think it's time to begin an orderly process of withdrawing our troops, start rebuilding our military and focusing on the challenges posed by Afghanistan," Clinton said during a Senate Armed Services hearing on Tuesday.
At that same hearing, Obama insisted, "The time to end the surge and to start bringing our troops home is now, not six months from now."
But Powell told Sawyer a withdrawal might not be that simple, no matter who is president next year.
"(The president) will have to continue to draw down at some pace. None of them are going to have the flexibility of just saying, 'We're out of here, turn off the switch, turn off the lights, we're leaving,'" he said. "They will have a situation before them."
On another hot topic, Powell rejected the idea of boycotting the opening ceremonies of the Olympics in China this summer.
"That's a judgment the president will have to make. I would not boycott the opening ceremony," Powell told Sawyer.
First reported on the Drudge Report, Sen. Clinton has called for a boycott of the opening ceremonies but not the Olympics overall, specifically citing China's reaction to recent protests in Tibet and inaction in Darfur.
"The violent clashes in Tibet and the failure of the Chinese government to use its full leverage with Sudan to stop the genocide in Darfur are opportunities for presidential leadership," Clinton said in a written statement.
"These events underscore why I believe the Bush administration has been wrong to downplay human rights in its policy toward China. At this time, and in light of recent events, I believe President Bush should not plan on attending the opening ceremonies in Beijing, absent major changes by the Chinese government."
After initially resisting making a direct call for a boycott, Obama, in a written statement, said, "If the Chinese do not take steps to help stop the genocide in Darfur and to respect the dignity, security, and human rights of the Tibetan people, then the president should boycott the opening ceremonies."
Set to begin on Aug. 8, 2008, the Beijing Olympics have been surrounded by controversy ever since the International Olympic Committee awarded China the Games.
House Speaker Nancy Pelosi, in an exclusive interview with "Good Morning America" co-anchor Robin Roberts, urged Bush to consider a boycott.
"I think boycotting the opening ceremony, which really gives respect to the Chinese government, is something that should be kept on the table," Pelosi, D-Calif., said. "I think the president might want to rethink this later, depending on what other heads of state do."
German Chancellor Angela Merkel has announced she will not attend the Olympic Games. British Prime Minister Gordon Brown said today that he will not attend the opening ceremonies in August.
Despite increasing calls for a boycott of the Olympic opening ceremony, Powell insists that such a move will not accomplish its objective.