The speaker of the House, Dennis Hastert, is fighting to hang on to his post in the wake of claims that Republican leaders in Congress failed to investigate a colleague who exchanged sexually explicit computer messages with teenagers who had served as pages on Capitol Hill.

In an appearance on the nationally syndicated “Rush Limbaugh Show,” Mr. Hastert defended his conduct and said he believes that Democrats helped create a public controversy over the emails and instant messages sent by a Republican congressman from Florida, Mark Foley, who resigned Friday.

“We have a story to tell and the Democrats have, in my view, have put this thing forward to try to block us from telling the story,” Mr. Hastert said. “They’re trying to put us on defense. The story is that we have protected this country against terrorism.”

The editorial page of the Washington Times and several prominent conservative activists, including David Bossie, Richard Viguerie, and Paul Weyrich, have urged Mr. Hastert to resign. He said yesterday that he would not do so because such a move could damage Republican chances at the polls next month.

“We are the insulation to protect this country, and if they get to me, it looks like they could affect our election as well,” Mr. Hastert, a former wrestling coach from Illinois, said. “If we lose this election, if this goes back over to the Democrats, it’ll come back in spades.”

On an election-related fund-raising trip through California yesterday, President Bush offered an unprompted pledge of support for Mr. Hastert.

“I know Denny Hastert, I meet with him a lot. He is a father, teacher, coach, who cares about the children of this country. I know that he wants all the facts to come out and he wants to ensure that these children up there on Capitol Hill are protected,” Mr. Bush said.

The president also offered his first public comments on Mr. Foley’s actions, condemning them as abhorrent.

“I was disgusted by the revelations and disappointed that he would violate the trust of the citizens who placed him in office,” Mr. Bush said.

It was not clear yesterday whether other party leaders would press Mr. Hastert to resign in an effort to stem the damage from the Foley affair.

In a radio interview, the House majority leader, John Boehner, acknowledged knowing about some of the less explicit messages and seemed to shift blame for the episode to Mr. Hastert.

“I believe I talked to the speaker and he told me it had been taken care of,” Mr. Boehner, a Republican of Ohio, told WLW–AM in Cincinnati. “My position is it’s in his corner, it’s his responsibility.”

While many on Capitol Hill viewed Mr. Boehner’s remarks as an effort to distance himself from Mr. Hastert, the majority leader later released a letter rejecting the calls for the speaker’s resignation and defending his actions.

Meanwhile, an attorney for Mr. Foley said yesterday that when the former congressman was between 13 and 15 years of age, he was molested by a clergyman. The lawyer, David Roth, did not identify the alleged perpetrator.

ABC News reported yesterday on additional sexual explicit messages Mr. Foley allegedly exchanged in 2003 with a high school student and former page. During a House vote, Mr. Foley reportedly exchanged virtual kisses with the boy and discussed having the boy drink alcohol at the congressman’s house.

Fox News also interviewed a former page who said he received sexual overtures via e-mail from Mr. Foley in the late 1990s. The page said he was 17 at the time.

Mr. Roth told reporters that Mr. Foley, who entered an inpatient alcohol treatment after resigning last week, never followed through on the talk of sex or alcohol in his messages with the teens. “Mark Foley has never had sexual contact with a minor,” the lawyer said.

One of the congressmen struggling to avoid the taint of the Foley scandal is Rep. Tom Reynolds, who represents suburban Buffalo. At a press conference Monday evening, Mr. Reynolds, who heads the fund-raising committee for House Republicans, said he acted appropriately after learning earlier this year of “overly friendly” e-mails sent by Mr. Foley to a Louisiana teenager.

“I took that to the speaker. I have done due diligence and I think that’s where I stand,” Mr. Reynolds said, according to video clips posted on the Web. “I don’t think I went wrong at all.”

During his appearance at Daemen College in Amherst, Mr. Reynolds was flanked by children of supporters. A reporter suggested that the youngsters should leave because of the sordid nature of the messages, but a parent interviewed by a local television station, WGRZ, said she was unconcerned.

Mr. Reynolds is also under fire because his chief of staff, Kirk Fordham, was formerly the top aide to Mr. Foley. According to a left-leaning Web site, AmericaBlog, Mr. Fordham encouraged ABC News not to report some of the more sordid e-mails in exchange for an exclusive on Mr. Foley’s resignation.

Mr. Reynolds told the Associated Press he was unaware of Mr. Fordham’s actions and referred questions to the aide, who did not respond to an e-mail message seeking comment yesterday.

Top Democrats denied involvement yesterday in breaking the Foley story, but one Democratic congressional campaign moved quickly to make political hay of the affair. In a new television commercial, a candidate for an open seat in Minnesota, Patricia Wetterling, denounced House leaders.

“It shocks the conscience,” the ad’s narrator declares. “Congressional leaders have admitted to covering up the predatory behavior of a congressman who used the Internet to molest children. For over a year, they knowingly ignored the welfare of children to protect their own power.”

The ad shows several recent newspaper headlines but mischaracterizes the statements of the political leaders who handled complaints about Mr. Foley.

Mr. Viguerie, a fund-raising guru for conservative causes, said he would persist in his calls for Mr. Hastert’s resignation, despite the political aid it would give to Democrats.

“These are classic moves by a sexual predator,” Mr. Viguerie said of the early e-mails, in which Mr. Foley asked for a teenager’s photo and commented on another teenager’s physique. “There’s clearly smoke and Denny Hastert’s the chief fireman in the House of Representatives and he should have taken action,” the Republican activist told CNN.

Asked about Republicans’ chances at the polls in November, Mr. Viguerie said, “I think they’re going to get their head handed to them.”