For four days, Sen. John McCain and his allies have accused Sen. Barack Obama of snubbing wounded soldiers by canceling a visit to a military hospital because he could not take reporters with him, despite no evidence that the charge is true.

The attacks are part of a newly aggressive McCain operation whose aim is to portray the Democratic presidential candidate as a craven politician more interested in his image than in ailing soldiers, a senior McCain adviser said. They come despite repeated pledges by the Republican that he will never question his rival's patriotism.

The essence of McCain's allegation is that Obama planned to take a media entourage, including television cameras, to Landstuhl Regional Medical Center in Germany during his week-long foreign trip, and that he canceled the visit when he learned he could not do so. "I know that, according to reports, that he wanted to bring media people and cameras and his campaign staffers," McCain said Monday night on CNN's "Larry King Live."

The Obama campaign has denied that was the reason he called off the visit. In fact, there is no evidence that he planned to take anyone to the American hospital other than a military adviser, whose status as a campaign staff member sparked last-minute concern among Pentagon officials that the visit would be an improper political event.

"Absolutely, unequivocally wrong," Obama spokesman Tommy Vietor said in an e-mail after McCain's comments to Larry King.

Despite serious and repeated queries about the charge over several days, McCain and his allies continued yesterday to question Obama's patriotism by focusing attention on the canceled hospital visit.

McCain's campaign released a statement from retired Sgt. Maj. Craig Layton, who worked as a commander at the hospital, who said: "If Senator Obama isn't comfortable meeting wounded American troops without his entourage, perhaps he does not have the experience necessary to serve as commander in chief."

McCain's advisers said they do not intend to back down from the charge, believing it an effective way to create a "narrative" about what they say is Obama's indifference toward the military.

McCain spokesman Tucker Bounds said again yesterday that the Republican's version of events is correct, and that Obama canceled the visit because he was not allowed to take reporters and cameras into the hospital.

"It is safe to say that, according to press reports, Barack Obama avoided, skipped, canceled the visit because of those reasons," he said. "We're not making a leap here."

Asked repeatedly for the "reports," Bounds provided three examples, none of which alleged that Obama had wanted to take members of the media to the hospital.

The McCain campaign has produced a television commercial that says that while in Germany, Obama "made time to go to the gym but canceled a visit with wounded troops. Seems the Pentagon wouldn't allow him to bring cameras." The commercial shows Obama shooting a basketball -- an event that happened earlier in the trip on a stopover in Kuwait, where the Democrat spoke to troops in a gym before grabbing a ball and taking a single shot. The military released the video footage.

A reconstruction of the circumstances surrounding Obama's decision not to visit Landstuhl, based on firsthand reporting from the trip, shows that his campaign never contemplated taking the media with him.

The first indication reporters got that Obama was planning, or had planned, to visit the hospital came last Thursday morning, shortly after the entourage arrived in Berlin. On the seats of the media bus were schedules for his stop in Germany and the final entry -- a Friday-morning departure -- indicated that the senator's plane would fly from Berlin to Ramstein Air Base.

When a reporter asked spokeswoman Linda Douglass that morning about the trip to Ramstein, she said that the trip had been considered but that Obama was not going to go. At that point, the campaign provided no other information.

Later that night, after Obama gave a speech in Berlin, a campaign source spoke about the canceled stop on the condition of anonymity. The official said that the trip was canceled after the Pentagon informed a campaign official that the visit would be considered a campaign event.

Overnight, the Obama team issued two statements, one from senior campaign official Robert Gibbs and the other from retired Air Force Maj. Gen. J. Scott Gration, an Obama foreign policy adviser who was on the trip.

Gibbs's statement said the hospital visit, which had been on the internal schedule for several weeks, was canceled because Obama decided it would be inappropriate to go there as part of a trip paid for by his campaign. Gration said the Pentagon had told the campaign that the visit would be seen as a political trip.

Those two statements, while not inconsistent, did not clarify whether the visit was canceled in reaction to Pentagon concerns or because of worries about appearances. They also opened Obama's camp to charges that it was offering slightly different reasons at different times.

Gibbs said yesterday that the campaign had planned to inform the traveling media members sometime on the morning of the flight to Ramstein that Obama was intending to visit the hospital but had made no plans to take reporters, including even the small, protective press pool that now accompanies him most places.

Reporters, he said, probably would have been able to get off the plane but not leave an air base facility close by. "We had made absolutely no arrangements to transport the press to the hospital," he said.

On Friday afternoon, en route from Berlin to Paris, Gibbs briefed reporters traveling with Obama. He noted that the candidate had visited wounded soldiers several weeks earlier at Walter Reed Army Medical Center in the District and at a combat support hospital while in Iraq earlier in the week -- both times without reporters.

At one point, a reporter asked, "Why not just say it is never inappropriate to visit men and women in service?" -- a key McCain charge -- "What is your response to that?"

Gibbs replied: "It is entirely likely that someone would have attacked us for having gone. And it is entirely likely -- and it has come about -- that people have attacked us for not going."

On Saturday in London, Obama addressed the controversy during a news conference. He said Pentagon concerns about Gration's status triggered the decision not to visit Landstuhl.

"We got notice that [Gration] would be treated as a campaign person, and it would therefore be perceived as political because he had endorsed my candidacy but he wasn't on the Senate staff," Obama said. "That triggered then a concern that maybe our visit was going to be perceived as political, and the last thing that I want to do is have injured soldiers and the staff at these wonderful institutions having to sort through whether this is political or not, or get caught in the crossfire between campaigns."

Obama's explanation, which came after more than a day of controversy, was the clearest in noting that it was Pentagon concerns about Gration accompanying him to the hospital that forced Obama to reconsider and, ultimately, cancel the visit.

Gibbs was asked yesterday about the continuingallegations from McCain that the real reason was a desire to bring a media entourage to the hospital.

"That's completely untrue, and I think, honestly, they know it's untrue," Gibbs said.