WASHINGTON - Fellow Democrats pointedly refused Tuesday to defend New York Rep. Anthony D. Weiner, telegraphing an unmistakable eagerness for him to resign after he admitted sending a lewd photo of himself to a woman via Twitter and lying about it.

Republicans swiftly sought political profit from Weiner's predicament, which threatened to deepen when conservative blogger Andrew Breitbart said he had a sexually explicit photo of the seven-term congressman.

His political career in extreme jeopardy, Weiner, 46, had no public appearances Tuesday. His spokesman did not respond to repeated requests for comment.

On Monday, after days of denials, he told a news conference he had engaged in "several inappropriate conversations conducted over Twitter, Facebook, e-mail, and occasionally on the phone with women I had met online."

Alternately apologetic and defiant, he said he neither met nor had physical relationships with any of them, and added, "I am not resigning."

In fact, there is little that party leaders can do to force an errant lawmaker to quit, though House Republicans have moved decisively in the last year to purge their ranks of two men who wound up in embarrassing situations.

Most Democrats maintained an uncomfortable silence about Weiner's future, part of what several senior congressional officials described as a hope that over a few days, he would reconsider his refusal to resign.

If not, several noted pointedly, Weiner's district might be eliminated when lines are adjusted before the 2012 elections to account for a population shift that will cost New York two House seats.

But Senate Majority Leader Harry Reid broke the silence.

"I wish there were some way that I can defend him, but I can't," the Nevada Democrat said. Asked what he would do if Weiner called for advice, Reid replied he would tell him "call somebody else."

Republicans sought political gain. Weiner's "actions and deception are unacceptable and he should resign," GOP chairman Reince Priebus said in a written statement.

"We do not need an investigation to know he lied and acted inappropriately, we need a resignation," Priebus said, referring to a request from House Minority Leader Nancy Pelosi (D., Calif.) for the House ethics committee to investigate the case.

Referring to Pelosi and Rep. Debbie Wasserman Schultz of Florida, the Democratic Party chairwoman, Priebus said they either "believe members of Congress are held to a different set of standards or they believe these actions demand his resignation."

Brad Woodhouse, a Democratic National Committee spokesman, referred a request for a comment to Wasserman Schultz's House office. He said the issue was a congressional one, but her spokesman declined to comment on whether Weiner should resign.

Separately, the Republican House and Senate campaign organizations called on Democrats to return donations that Weiner had made to them.

"Does ... Democrat Senate candidate Joe Donnelly (D., Ind.) plan to return the $5,000 he took from his friend Weiner in order to fund his political campaigns?" asked the National Republican Senatorial Committee. There was no immediate reply from Donnelly, a second-term House member who recently announced he would run for the Senate in 2012.

In the House, Rep. Betty Sutton (D., Ohio) said through an aide that she would donate to charity a $1,000 contribution she received from Weiner last year.

Demanding the return of cash from troubled donors has become a standard political tactic in recent years, practiced by both parties.

But the other facts in Weiner's case were anything but routine.

Instead, they reflected the growing impact of social media and little-known websites on the political fortunes of the nation's most powerful elected officials, in this case, a man with ambitions of becoming mayor of New York.

Despite fielding numerous questions Monday, some of them intensely personal about his marriage, Weiner left gaps at his news conference.

Among them, when asked whether he could guarantee that there was no X-rated photo in existence of himself, he replied: "No, I cannot."

That issue was first broached by Breitbart, who showed up at Weiner's news conference Monday before the congressman did.

In an interview Tuesday, Breitbart said he had not yet released a sexually explicit photo taken of the congressman unclothed.

He said he would consider releasing the picture if he concluded that Weiner's staff tried to disparage any of the "innocent women" with whom the congressman flirted online.

At his news conference, Weiner apologized to the women and to all he misled with his earlier denials, but most often to his wife, Huma Abedin, who was not present.

Abedin, deputy chief of staff to Secretary of State Hillary Rodham Clinton, is well-known in her own right in Democratic circles. Some party officials said that was a factor in the general unwillingness to call for Weiner's resignation.