TOLEDO, Ohio (CNN) -- Sen. John McCain on Thursday denied assertions published in The New York Times that he once had a close relationship with a female lobbyist whose clients had business before his Senate committee.

"I'm disappointed in The New York Times piece. It's not true," he told reporters in Toledo, Ohio, his wife, Cindy, standing by his side.

He added that he has never "done anything that would betray the public trust or make a decision" that would favor a particular group.

His wife added that her husband always puts family and country first, and is "a man of great character."

The New York Times issued a statement Thursday saying it stands by its reporting and that "the story speaks for itself."

The newspaper reported in its online edition Wednesday that aides to McCain's 2000 presidential campaign were so worried about the relationship that they confronted McCain and the lobbyist, Vicki Iseman.

Also, some McCain advisers were concerned that the relationship had become romantic, The New York Times reported.

"A former campaign adviser described being instructed to keep Ms. Iseman away from the senator at public events, while a Senate aide recalled plans to limit Ms. Iseman's access to his offices," the paper reported.

The paper's assertions were part of a larger article on McCain's relationships with and stances toward lobbyists and special interests.

The Arizona senator has dominated the Republican primaries, handily pulling away from former Arkansas Gov. Mike Huckabee in the race for the GOP presidential nomination.

McCain said in a news conference Thursday that he never had discussions with any staffers about an inappropriate relationship with Iseman. He also denied having a romantic relationship with her. If staffers had such concerns, McCain told reporters, they never conveyed them to him.

The New York Times quoted what it said were two admittedly "disillusioned" former McCain associates who said they approached the senator and the lobbyist about their concerns. "Both said Mr. McCain acknowledged behaving inappropriately," the newspaper reported.

McCain further described his relationship with Iseman as a friendship and said he had "seen her on occasion, particularly at receptions and fundraisers and appearances before the committee." Asked if he was closer to Iseman than he was other lobbyists, McCain flatly said no.

McCain's former top political adviser, John Weaver, told the newspaper that he met with Iseman at Washington's Union Station during McCain's first presidential bid. He asked her to stay away from the senator, the paper reported, because McCain was running on a platform of political reform and shunning special interests.

Iseman represented telecommunications companies with business before the Senate Commerce Committee that McCain led, according to the newspaper.

"Ms. Iseman's involvement in the campaign, it was felt by us, could undermine that effort," Weaver told the Times.

In a Thursday interview with CNN, Weaver said he approached Iseman because she was telling people she had special access to and influence with McCain.

The New York Times story does not claim Weaver and Iseman discussed any romantic relationship, and Weaver told CNN they never talked about it because "there was no reason to."

"My concern wasn't about anything John had done; it was about her comments. It was about access she claimed to have had," Weaver told CNN.

Weaver left the McCain camp in summer 2007, but he said he still talks to the senator's campaign officials daily.

Iseman acknowledged the Union Station meeting but disputed Weaver's account, according to The New York Times.

"I never discussed with him alleged things I had 'told people,' that had made their way 'back to' him," Iseman told the newspaper in an e-mail. She added that she never received special treatment from McCain's office, according to the paper.

As for claims that McCain's advisers were concerned about a possible romantic relationship, Iseman told the newspaper the claims were unfounded.

Iseman works for the consulting firm Alcalde & Fay. Among its clients are several large telecommunications firms. Iseman's name has been removed from the company's staff Web page and requests for comment from CNN have not been answered. Attempts to reach Iseman also were unsuccessful.

In his Thursday news conference, McCain called Weaver "a friend." Of the alleged Union Station meeting, he said, "I don't know anything about it."

"Since it was in The New York Times, I don't take it at face value," he said.

Hours after the newspaper posted its story, McCain's advisers challenged the accuracy of the Times' article and questioned the newspaper's motivation.

Campaign spokeswoman Jill Hazelbaker said in a statement that the newspaper had engaged in a "smear campaign" and that nothing in the story suggests "that John McCain ever violated the principles that have guided his career."

One of McCain's senior advisers, Charlie Black, told CNN that the campaign first learned in October the paper was working on a story about McCain's relationship with Iseman.

He said that information and documents provided to the paper disputes suggestions McCain tried to use his influence to help Iseman.

Black further said The New York Times was a liberal newspaper that was printing "rumors and gossip" in what he described as a partisan attack on the conservative McCain.

"He doesn't do favors for anyone," Black said of McCain.