In an interview with Newsweek's Richard Wolffe on July 26, Sen. Barack Obama said his 16-month timetable for withdrawal of U.S. troops from Iraq wouldn't involve all of the U.S. forces there.

"[Iraqi Prime Minister Nouri al-] Maliki recognizes that they're going to need our help for some time to come, as our commanders insist, but that help is of the sort that is consistent with the kind of phased withdrawal I have promoted," Mr. Obama said. "We're going to have to provide them with logistical support, intelligence support. We're going to have to have a very capable counterterrorism strike force. We're going to have to continue to train their army and police to make them more effective."

When Mr. Wolffe asked him how large this residual force might be, Sen. Obama replied: "I do think that's entirely conditions based. It's hard to anticipate where we may be six months from now, or a year and a half from now."

Obama advisers told columnist Robert Novak there may be up to 50,000 soldiers in that residual force. In the current issue of Foreign Affairs, Colin Kahl, an Obama adviser, said that residual force might initially consist of 12 brigades.

U.S. commanders think a 16-month plan to withdraw all U.S. troops is nutty because it would require them to leave most of their equipment behind, ABC's Martha Raddatz reported in a broadcast July 11.

U.S. commanders also object strenuously to any withdrawal plan that isn't based on conditions on the ground. But if there is to be a residual force, size and composition to be determined "entirely" by conditions, then there is little practical difference between what Mr. Obama is saying now about Iraq, and what Sen. John McCain has been saying all along.

There is a difference of emphasis. Mr. Obama has a timetable for withdrawal from Iraq, which he now says he's willing to modify if circumstances warrant. Mr. McCain says troop withdrawals should be based entirely on conditions, but conditions in Iraq have improved so much we can now have a "time horizon" for withdrawal of most of the troops. I leave it to those who speculate about how many angels can dance on the point of a pin to define the difference between a "timetable" and a "time horizon."

This happy convergence is a product of the enormous success of the troop surge, of which Mr. McCain was an early supporter and which Mr. Obama opposed. Mr. McCain was right. Mr. Obama was wrong. Mr. Obama's unwillingness to admit this may be a greater disqualification to be commander-in-chief than his poor strategic judgment.

"To listen to Barack Obama attempt to explain his views on Iraq and the so-called surge is becoming, for those of us who have followed his responses over the last 18 months, something of a spectacle," wrote Peter Wehner in Commentary magazine. "With every effort, it seems, he is compounding his mistakes in judgment with intellectually dishonest answers, ones which melt away under even minimal scrutiny."

On "Meet the Press" last Sunday, Tom Brokaw reminded Mr. Obama that on the day the surge strategy was announced, he had said: "I am not persuaded that 20,000 additional troops in Iraq is going to solve the sectarian violence there; in fact, I think it'll do the reverse."

To which Mr. Obama responded: "I know that there's that little snippet you ran, but there were also statements made during the course of this debate in which I said there's no doubt that additional U.S. troops could temporarily quell the violence."

But Mr. Obama often said the surge would make the violence in Iraq worse, most recently in November 2007, two months after there was a substantial dropoff in violence. Mr. Obama said then: "Not only have we not seen improvements, but we're actually worsening, potentially, a situation there."

It wasn't until a Democratic debate on Jan. 5 of this year that Mr. Obama acknowledged violence was diminishing: "I said at the time, when I opposed the surge, that given how wonderfully our troops perform, then we would see an improvement in the security situation and we would see a reduction in the violence," he said.

But Mr. Obama had said precisely the opposite at the time, and for six months thereafter. What he did in the "Meet the Press" interview, Mr. Wehner said, "is to provide a misleading answer to a previously dishonest answer, in an effort to cover up his spectacularly wrong prediction."

A man who admits no mistakes is very different from a man who makes no mistakes.