April 9, 2008 -- Retired Gen. Colin Powell insists he hasn't yet decided who he'll back in the 2008 presidential election.

"I'm looking at all three candidates," Powell said in an exclusive interview with Diane Sawyer for Thursday's "Good Morning America" on ABC. "I know them all very, very well. I consider myself a friend of each and every one of them. And I have not decided who I will vote for yet."

Powell, who served as President Bush's first secretary of state, is a Republican, but that apparently is not enough to sway him toward Sen. John McCain, R-Ariz., the GOP's presumptive nominee.

McCain has staked much of his presidential prospects on the success of the surge strategy in Iraq, a subject of great debate in Washington this week as Gen. David Petraeus took his case to Capitol Hill.

"The United States Armed Forces are very, very stretched. It appears that after the surge is over, we're going to go down to 140,000 troops in Iraq. That's 10,000 more than we had before the surge," Powell observed, reacting to the testimony Petraeus delivered over two days.

"There is something of a continued surge there with that extra 10,000. And based on what Gen. Petraeus has said, he wants to let the surge troops go by July and then take 45 days to see what it looks like, and then begin a process of assessment. Well, that tells me that we know what the administration strategy is going to be through the end of the term of the administration. And that is, we're going to maintain a very significant presence," Powell said.

Extended Presence in Iraq, Trouble in Afghanistan Concern Powell

Powell, who served as chairman of the Joint Chiefs of Staff during the administration of President George H.W. Bush and the first Gulf War, expressed concern over the burden an extended stay in Iraq would put on the troops and the country's military forces.

"It's going to be far more than the 100,000 that Secretary [of Defense Robert] Gates was hoping for. It's going to be like 130,000 or 140,000. That is an extremely difficult burden for the United States Army, the United States Marine Corps, to keep up," Powell told "Good Morning America."

Powell also expressed reservations about the two-front combat in which the United States finds itself: surging in Iraq while trying to maintain control in Afghanistan.

"We have responsibilities in Afghanistan. And in some ways, Afghanistan is more difficult than Iraq. You have the tribal problems. You had drug lords running around ... and al Qaeda and the Taliban are making a resurgence," Powell said.

Next President's Challenge

Sawyer pressed Powell on the differences between the presidential contenders on the critical issue of Iraq.

"I'll tell you what they're all going to face — whichever one of them becomes president on Jan. 21 of 2009 — they will face a military force, a United States military force, that cannot sustain, continue to sustain, 140,000 people deployed in Iraq, and the 20 (to) 25,000 people we have deployed in Afghanistan, and our other deployments," Powell said.

In a recent speech, McCain cast America's commitment to Iraq as a "moral responsibility," arguing that a genocidal civil war could ensue if U.S. troops are withdrawn too soon.

"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."

Powell Rejects Olympic Boycott

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.

Powell: Boycotts Don't Work

Despite increasing calls for a boycott of the Olympic opening ceremony, Powell insists that such a move will not accomplish its objective.

"We always are aware and have been aware of Chinese human rights problems. And I think if you start to take this kind of action, it doesn't really serve the purpose of human rights," Powell told "Good Morning America."

"What is accomplished by boycotting the opening ceremony?" Powell asked rhetorically. "I don't think that makes the situation any better. It probably makes the situation a little more difficult for the Chinese because they will pull back even more."

Powell encouraged China to begin a dialogue with the Dalai Lama, the exiled spiritual leader of Tibet.

"I think we ought (to) recognize that these protests are legitimate, recognize that the Chinese ought to move forward and start having a dialogue with the Dalai Lama, and not just say, 'We're not going to talk to you.' (The) Dalai Lama has indicated flexibility. And I think that's what the Chinese should do," he said. "But I don't think that these kinds of actions, such as boycotting an opening ceremony, or even perhaps thinking twice about sending your team to the Olympics, has the desired effect.

"I very much supported in 2001, when I was secretary of state, that we give the Olympics to the Chinese because I thought it would put them under a spotlight. And they have responded to that spotlight," he said. "But they haven't with respect to Tibet. And these demonstrations show the Chinese leadership that the world is watching this."

Race and the Race

Returning to presidential politics, Powell condemned controversial remarks by Rev. Jeremiah Wright, Obama's pastor of 20 years, as "deplorable" but complimented the Democratic candidate for his speech on race that followed in the aftermath.

"Rev. Wright is also somebody who has made enormous contributions in his community and has turned a lot of lives around," Powell said, "And so, I have to put that in context with these very offensive comments that he made, which I reject out of hand."

Powell added that he does not know Wright, and praised Obama's response.

"I think that Sen. Obama handled the issue well . . . he didn't look the other way. He didn't wait for the, for the, you know, for the storm to go over. He went on television, and I thought, gave a very, very thoughtful, direct speech. And he didn't abandon the minister who brought him closer to his faith," Powell told Sawyer.

Powell, who has been mentioned as a possible vice presidential candidate in almost every election since he retired from military service and public life, expressed admiration for Obama.

"It was a good (speech)," Powell said. "I admired him for giving it. And I agreed with much of what he said."