ABC News' David Wright reports from Cartagena, Colombia. Sen. John McCain has set himself a difficult task on his trip to Latin America: to score political points against rival Barack Obama without criticizing him directly.
"I believe that partisanship ends at the waters edge," McCain said emphatically, when asked about Obama at a press conference at the Colombian Presidential retreat here.
But on the inaugural flight of the Straight Talk Express airborne edition McCain felt freer to let loose.
On the plane, he blasted Obamas opposition to the proposed Colombia free trade deal.
"Hes a protectionist and anti-free trade," McCain said. "Now he has switched, I mean remarkably, from saying that he would unilaterally renegotiate the North American Free Trade Agreement in the strongest possible terms in Ohio he went to North Carolina and said well, Im for free trade.
"It wouldnt surprise me to see him switch on this one," McCain said.
McCain bristled at the comments on "Face the Nation" last weekend by an Obama supporter, retired general Wesley Clark, who belittled the relevance of McCains wartime experience as a qualification for the Presidency.
"I think its up to Sen. Obama now not only to repudiate him but to cut him loose," McCain said.
McCain became visibly angry when I asked him to explain how his Vietnam experience prepared him for the Presidency.
"Please," he said, recoiling back in his seat in distaste at the very question.
McCain allies Sen. Lindsey Graham stepped in to rescue him. Graham expressed admiration for McCains stance on the treatment of detainees in US custody.
"That to me is a classic example of how his military experience helped him shape public policy in a way no other senator could have done, Graham said.
Sen. Joseph Lieberman, also traveling on the trip, expressed admiration for McCains wartime service as well.
McCain then collected himself and apologized for his initial reaction.
"I kind of reacted the way I did because I have a reluctance to talk about my experiences," he said, noting that he has huge admiration for the "heroes" who served with him in the POW camp and said the experience taught him to love the U.S. because he missed it so much.
"I am always reluctant to talk about these things," McCain said.
Asked about one of his former jailors from the notorious Hanoi Hilton who has now endorsed his candidacy for President, McCain chuckled.
"Yeah, I saw that," he said. "He also said that he and I used to have these nice, long philosophical chats. The ones that I recall is, confess or else."