SOMEWHERE in NORTHERN IOWA — The unthinkable has happened. Senator John McCain met a question, while sitting with reporters on his bus as it rumbled through Iowa today, that he couldn’t – or perhaps wouldn’t – answer.

Did he support the distribution of taxpayer-subsidized condoms in Africa to fight the transmission of H.I.V.?

What followed was a long series of awkward pauses, glances up to the ceiling and the image of one of Mr. McCain’s aides, standing off to the back, urgently motioning his press secretary to come to Mr. McCain’s side.

The upshot was that Mr. McCain said he did not know this subject well, did not know his position on it, and relied on the advice of Senator Tom Coburn, a physician and Republican from Oklahoma.

His press secretary, Brian Jones, later reported that Mr. McCain had a record of voting against using government money to finance the distribution of condoms.

All this took place on the second day of the reprise of the “Straight Talk Express” bus trips that Mr. McCain made a central part of his campaign in 2000. It also comes as Mr. McCain has eagerly been trying to ease strains with social conservatives in the party who, for the most part, do not support using government money to pay for condoms.

A transcript of the encounter follows. (Weaver is John Weaver, his senior adviser, and Brian is Mr. Jones, his press secretary):

Reporter: “Should U.S. taxpayer money go to places like Africa to fund contraception to prevent AIDS?” Mr. McCain: “Well I think it’s a combination. The guy I really respect on this is Dr. Coburn. He believes – and I was just reading the thing he wrote– that you should do what you can to encourage abstinence where there is going to be sexual activity. Where that doesn’t succeed, than he thinks that we should employ contraceptives as well. But I agree with him that the first priority is on abstinence. I look to people like Dr. Coburn. I’m not very wise on it.” (Mr. McCain turns to take a question on Iraq, but a moment later looks back to the reporter who asked him about AIDS.) Mr. McCain: “I haven’t thought about it. Before I give you an answer, let me think about. Let me think about it a little bit because I never got a question about it before. I don’t know if I would use taxpayers’ money for it.” Q: “What about grants for sex education in the United States? Should they include instructions about using contraceptives? Or should it be Bush’s policy, which is just abstinence?” Mr. McCain: (Long pause) “Ahhh. I think I support the president’s policy.” Q: “So no contraception, no counseling on contraception. Just abstinence. Do you think contraceptives help stop the spread of HIV?” Mr. McCain: (Long pause) “You’ve stumped me.” Q: “I mean, I think you’d probably agree it probably does help stop it?” Mr. McCain: (Laughs) “Are we on the Straight Talk express? I’m not informed enough on it. Let me find out. You know, I’m sure I’ve taken a position on it on the past. I have to find out what my position was. Brian, would you find out what my position is on contraception – I’m sure I’m opposed to government spending on it, I’m sure I support the president’s policies on it.” Q: “But you would agree that condoms do stop the spread of sexually transmitted diseases. Would you say: ‘No, we’re not going to distribute them,’ knowing that?” Mr. McCain: (Twelve-second pause) “Get me Coburn’s thing, ask Weaver to get me Coburn’s paper that he just gave me in the last couple of days. I’ve never gotten into these issues before.”

This went on for a few more moments until a reporter from the Chicago Tribune broke in and asked Mr. McCain about the weight of a pig that he saw at the Iowa State Fair last year.