"It's not true," the likely Republican presidential nominee said of the report that implied a romantic link with telecommunications lobbyist Vicki Iseman and that suggested McCain pushed legislation that would have benefited her clients.

"At no time have I ever done anything that would betray the public trust," said McCain, who described the lobbyist as a friend.

McCain and his wife, Cindy, at a news conference in Ohio, said they were disappointed the New York Times ran the article, and his campaign referred to a "smear campaign" in the midst of the presidential race.

The report, which the Times initially posted on its Web site Wednesday, and a subsequent article in the Washington Post raise questions about core themes of McCain's campaign - that he would bring integrity to the White House as well as a record of changing business-as-usual Washington ways.

Even the suggestion of marital impropriety - though rejected by both McCain and his wife - could risk further damaging his acrimonious relationship with social conservatives.

However, there were early signs that the brouhaha might actually help McCain solidify the conservative base.

Rush Limbaugh, an unrelenting conservative critic of McCain, told his radio audience yesterday that "there is nothing in it here that you can say is true." He accused the Times of "trying to take him out."

"The fact that it was the New York Times and the lack of sufficient detail undermines the credibility of the story," said Christopher LaCivita, a Republican strategist in Virginia unaffiliated with the McCain campaign, noting that the Times is considered a liberal bogeyman for the GOP rank-and-file.

By yesterday afternoon, McCain had begun a fund-raising appeal based on the article.

"We need your help to counteract the liberal establishment and fight back against the New York Times by making an immediate contribution today," campaign manager Rick Davis wrote in e-mail to supporters.

"We think the story speaks for itself," Times executive editor Bill Keller said in a statement.

The episode does give Democrats an opening to try to exploit McCain's decades-long ties to Washington even though he is known as a lawmaker who is willing to stand up to special interests.

It's a reputation he has carefully honed after the 1991 Keating Five influence-peddling scandal. The Senate cited him for "poor judgment" in that matter - in which he intervened on behalf of a troubled bank whose owner was a big campaign contributor - but took no further action.

The Democratic National Committee said yesterday in a statement: "After 25 years in Washington, the real John McCain is just like the other D.C. insiders he rails against on the campaign trail. John McCain's 'Do as I say, not as I do' approach to ethics and lobbying reform can be called a lot of things. 'Straight talk' isn't one of them."

Aware of the high stakes, McCain officials acted quickly. The campaign distributed statements deriding the article, deployed senior advisers to TV news shows, and arranged a news conference for McCain and his wife of nearly 28 years to address the matter as they campaigned in Toledo.

In the article, months in the making, anonymous McCain aides were quoted as having urged McCain and Iseman to stay away from each other in the run-up to his failed presidential campaign in 2000.

In the article in the Washington Post, John Weaver, a longtime aide who split with McCain last year, said he met with Iseman and asked her to steer clear of the senator eight years ago.

Both stories said aides worried about the appearance of McCain having close ties to a lobbyist with business before his Commerce Committee. The stories also said McCain wrote letters and pushed legislation involving television-station ownership that would have benefited Iseman's clients.

McCain said that he was not aware of Weaver's meeting with Iseman and that no staffers had indicated to him they were concerned about his association with her. "If they were, they didn't communicate that to me," McCain said yesterday.

Efforts to reach Iseman for comment were unsuccessful.