Although he pledged to stay and fight, Democratic Rep. Anthony Weiner’s political survival was in question Tuesday as the leaders of his own party continued to distance themselves from the disgraced New York lawmaker and as Republicans persisted in calling for his resignation.

In an ominous sign of Weiner’s prospects, Sen. Harry M. Reid (Nev.), the highest-ranking Senate Democrat, refused to defend Weiner, quipping that his advice to the congressman, if sought, would be: “Call someone else.”

“I wish there was some way I can defend him, but I can’t,” Reid said in a sentiment that echoed throughout Capitol Hill.

Meanwhile, Republicans were flatly calling for Weiner to step down. “Congressman Weiner and his constituents will make that decision,” said House Majority Leader Eric Cantor (Va.). “I certainly don’t condone his activity, and I think he should resign.”

Weiner became more and more isolated as the fallout settled from his admission a day earlier that he had engaged in sexually explicit exchanges with women he met online. While the means by which he committed his transgressions represent a new frontier for Washington scandal, the questions and challenges ahead of him are as old as controversy itself. Scandals move quickly in the Internet era. Weathering them takes a combination of personal resolve, crisis-management skills and the right political circumstances.

Weiner could need all three to survive.

The New York Democrat has said he will not forfeit his seat, but that resolve is certain to be tested from a number of directions: a coming storm inside the Democratic caucus, whose members will be returning to Washington next week from a recess; political heat from Republicans; and a likely investigation by the House Ethics Committee into whether, among other things, he used government resources to conduct the seamy exchanges.

House Minority Leader Nancy Pelosi (D-Calif.) — who last week expressed confidence in Weiner — formally requested that investigation in a letter Tuesday to the ethics panel.

Weiner didn’t do himself any good when he assured House leaders last week that his Twitter account had been hacked and that he had not sent the suggestive picture that started the furor.

Rep. Steve Israel (N.Y.), the chairman of the Democratic Congressional Campaign Committee, issued a statement indicating that his caucus has no appetite for defending Weiner — and suggesting, in none-too-subtle terms, that it wouldn’t be sorry to see him leave.

“Ultimately, Anthony and his constituents will make a judgment about his future,” Israel said, condemning Weiner’s “deep personal failure” in engaging in online sexual exchanges with at least six women over the past three years.

Meanwhile, the GOP’s campaign operation was looking for opportunities to taint other House Democrats by association with Weiner.

The National Republican Congressional Committee sent news releases calling on 16 Democrats who have taken contributions from Weiner to return the money. One of them, Rep. Betty Sutton (Ohio), announced that she would give $1,000 to local charities to rid herself of the amount she had received from Weiner’s political action committee.

Weighing his future

If Weiner decides to stay and fight, he must weigh the very definition of what it means to survive. In his case, the scandal almost certainly means he has no chance of realizing his ambition of becoming New York City mayor, a post he didn’t win in 2005 and still aspires to.

He is not the first politician left to ponder whether what remains of his political career is worth what it will take to salvage it.

If he chooses to stay in Congress, Weiner will undoubtedly face weeks or months of unrelenting and intrusive questions about uncomfortable personal matters, as well as the possible ethics inquiry, which could ultimately be made public. Questions about his marriage to Huma Abedin, Secretary of State Hillary Rodham Clinton’s senior adviser, will continue to be chewed over publicly.

“We all know what the picture is going to be for the next weeks, months, years,” said one longtime Democratic congressional aide who has seen many such episodes. “The question is, does he want to go through it?”

Some lawmakers who have been the subject of similarly unflattering scandals depart quickly, as Rep. Chris Lee (R-N.Y.) did in February, when it was revealed that he had sent shirtless photos of himself to a woman he met on Craigslist.

Yet there have been politicians who have fought, survived and resurrected their reputations — most extraordinarily, former president Bill Clinton, who did so after the Monica Lewinsky scandal.

Sen. David Vitter (R-La.) was easily reelected in 2010 after his phone number was found in the records of a D.C. prostitution service and he apologized for “a very serious sin in my past.”

Then-Sen. John Ensign (R-Nev.) had also entertained hopes that his state’s voters would give him another chance after the 2009 revelation that he had had an extramarital affair with a former campaign staffer. But Ensign resigned in April amid a Senate Ethics Committee investigation of payments that his parents made to the woman’s husband and his own efforts to find lobbying work for the husband, who was also a former aide.

On the other hand, former New York governor Eliot L. Spitzer (D), who resigned after he was exposed in 2008 as the client of a prostitution service, reinvented himself as a commentator and CNN talk show host.

‘Didn’t think it was worth it’

In 1989, then-House Majority Whip Tony Coelho (D-Calif.) left Congress rather than face what promised to be a prolonged investigation of his purchase of junk bonds with the help of a savings-and-loan executive. The Justice Department investigated, but it did not bring charges.

But Coelho said he does not regret the decision to leave, recalling: “I didn’t think, as a result of that situation, that I would end up being speaker. And in my case, I didn’t think it was worth it to stay.”

“He’s lost his influence; he’s not going to be mayor,” Coelho said of Weiner. But if he chooses to fight and survives, Coelho predicted, “the public will lose interest in him quickly.”

Despite the racy Internet photos and e-mails, Coelho said, “it’s just not that interesting a story.”