Last Thursday morning at the Bagel Oasis in Rep. Anthony Weiner’s district of Queens, Mike Boccomino waited to order coffee as an NY1 news anchor on the TV above the counter remarked about “the enormous amount of oxygen” the congressman’s lewd picture scandal has received.

A newspaper rack next to the Hostess snack cakes offered diminishing piles of the New York Post (“Battle of the Bulge. Weiner Exposed, Admits: Could Be My Weiner in Twitter Pic”) and the Daily News (“Weiner’s Pickle: Says Sexy Pic Might Be Him But He Didn’t Send it. Huh?”) .

Weiner, the star of so many viral YouTube clips excoriating Republicans and the go-to source for a dynamite quote — “that special Weiner spin,” he called it — had finally reached his full saturation point.

Just not the way he had expected.

Weiner’s clamorous, choked-up media-circus admission on Monday afternoon that he had, despite his multiple denials, used Twitter to send a photo of his crotch to a college student in Seattle effectively gave his media profile a status update. No longer is he the liberal blogosphere’s and cable television’s favorite champion of left-leaning causes. Instead he is yet another straying congressman, who publicly lied about sending private inappropriate messages to at least half a dozen women across the country.

That change has been devastating to Weiner’s mayoral ambitions in New York, which seemed highly realistic only a few days ago, and throws into serious question his ability to stay in office, which he has vowed to do.

But even before his teary live-feed admission to his friends and family — especially his wife, Huma Abedin, a close aide to Secretary of State Hillary Rodham Clinton — colleagues in the New York congressional delegation said they had serious reservations about the incongruity between his high media profile and what they considered his low impact in pushing legislation behind the scenes.

Several said in interviews that they regarded his diminished stature as more of a loss to cable television bookers than to the Democratic legislative agenda.

As the television explained Weiner’s unfolding saga in the Bagel Oasis last week, some voters in his district had already written him off.

“He doesn’t qualify, not after this,” said Boccomino, 64, a retired schoolteacher. “You’re out, Anthony. No way.”

Phillip Stamatis, 20, piling sesame and everything bagels into a brown paper bag, agreed. “Weiner spoke at my elementary school graduation. He seemed like a nice guy,” Stamatis said. “I would have voted for him if it wasn’t for this.”

Rising through the ranks

This was not supposed to happen to Weiner. With his sharp tongue, middle-class sensibilities, self-deprecating humor and Clinton connections, his supporters thought he was destined for great things.

In 1985, Weiner — who roomed in college with future “Daily Show” host Jon Stewart and originally considered a job as a weatherman — interned for then-Rep. Charles E. Schumer, an ambitious Democrat representing the Park Slope neighborhood where Weiner grew up.

He soon rose through the ranks and wanted to run for office himself, even looking outside of New York for opportunities. But Schumer counseled his protege that he needed to do more spadework and make a name for himself in the district. Weiner took the advice. And when the City Council expanded in 1992, he won a seat, becoming its youngest member ever.

Weiner picked fights with Republican Mayor Rudolph W. Giuliani and made friends with reporters. Like Schumer, he knew how to appear in and shape stories. In 1998, when Schumer moved to the Senate, Weiner followed in his footsteps, taking his seat in the House. But unlike Schumer, who coupled his high media profile with ceaseless deal-making, issue expertise and legwork, Weiner kept his focus primarily on the press. His goal was Gracie Mansion, and as a congressman, he had the media platform to get there.

Weiner took his shot at mayor in 2005. Although he didn’t win, it worked out better than he could have dreamed. After narrowly losing a runoff to Bronx Democrat Fernando Ferrer, he decided not to contest the results and gracefully bowed out in the name of party unity. That built up reserves of goodwill that could be better spent down the road than in a doomed race against powerful Mayor Michael R. Bloomberg (I).

Weiner returned to Congress, but it was clear to everyone who paid attention that becoming mayor remained his objective. Bloomberg’s surprise decision to run for a third term in 2009 dealt Weiner a setback, but he improvised, writing an awkward New York Times editorial saying that he could do more for New York in Washington than in New York.

Then, in the fall of 2009, Weiner identified a political opportunity in the debate over health-care reform.

When the bill made it to the House Energy and Commerce Committee, a panel Weiner belonged to, then-Chairman Henry A. Waxman (D-Calif.) realized that he didn’t have the votes to pass the bill with the robust public option demanded by many on the political left. To get it out of committee, he needed support of moderate “Blue Dog” Democrats, and that meant he needed to go for a less-ambitious public option. Then, to the surprise of his colleagues, Weiner objected.

“Anthony wanted to go to the House floor to present a single-payer bill,” Waxman said in an interview.

That was shocking news for some of his liberal colleagues in the House, who said they had worked for years on single payer without hearing a peep from him. It was also unwelcome.

“To call a vote in that environment would have damaged single payer for the future,” said one representative involved in the negotiations. “We were trying to protect it from a vote because we saw the handwriting on the wall.”

But more moderate Democrats also worried that taking a single-payer vote to the floor would endanger the passage of the health-care bill altogether. It would hand Republican opponents ammunition to argue that the Democrat’s bill in the House was just the first step in their goal of a total government takeover.

“There were people who were afraid to go to the House floor and lose,” Waxman said.

On Nov. 5, 2009, Reps. Dennis J. Kucinich (D-Ohio) and John Conyers Jr. (D-Mich.) sent a letter to colleagues saying, “We do not want a weak bill brought forward in a hostile climate to unwittingly accomplish what would be interpreted as a defeat for single payer.”

Weiner wouldn’t budge and the problem was kicked up to then-Speaker Nancy Pelosi (D-Calif.), who, according to one representative present at the time of the negotiations, told Weiner to “back off.” Pelosi, Waxman said, “thought it would be unhelpful to have a vote on single payer.”

Weiner demanded that Pelosi give him something to save face, so she offered public praise and essentially said that he was a hero in the fight for a robust public option. But that wasn’t the real prize.

With his new cred, Weiner became the voice of a principled opposition to a watered-down health-care bill. He took his show on MSNBC and left-wing cable shows and into the liberal blogosphere. A star was born, and for a potential mayoral candidate looking to court wealthy Manhattan donors and liberal voters, it was the perfect complement to the middle-class, ethnic white base he had in the outer boroughs.

“There was a lot of resentment that he became the national progressive voice,” said one of the resentful liberal representatives. “And he had never been especially progressive before.”

Other members of the New York delegation expressed similar frustration with Weiner last year, during the efforts to pass a bill to cover the cost of medical care for rescue workers and others who suffered ailments related to the toxic fumes emitted after the Sept. 11, 2001, attacks on the World Trade Center.

“He almost blew up the [expletive] bill,” said one representative from New York, who spoke on the condition of anonymity.

According to the representative, Democrats worked for months with GOP Rep. Peter T. King (N.Y.) to bring more Republicans on board. Then, when the bill had a procedural setback, Weiner, who had not been especially active behind the scenes, took to the floor to lambaste his Republican colleague.

“Peter King was our ally!” the representative said.

The video went viral and reinforced Weiner’s bona fides as a Democratic firebrand.

A future in question

On Sunday morning, that reputation had already been mostly eclipsed by talk of underwear, Twitter, sexting and college students. As much of New York’s political establishment marched along 5th Avenue for the Israel Day Parade — an occasion that Weiner, one of Congress’s staunchest defenders of Israel, rarely missed — the lawmaker was nowhere to be seen.

Public Advocate Bill de Blasio, considered a potential mayoral rival of Weiner’s, declined, gleefully, to comment. There was nothing he could do that the city’s media weren’t doing already.

When Gov. Andrew M. Cuomo (D) showed up, the pack of reporters asked him first about Weiner’s future.

“It’s going to be up to the congressman how he handles this and people will have the opinion when they actually have the facts,” Cuomo said. As he looked for his place among other elected officials, Sen. Frank R. Lautenberg (D-N.J.) already was speaking of Weiner in the past tense.

“I feel badly for him,” the senator said. “He was young and bright, perhaps on his way to higher office.”

The politicians followed the parade route up Central Park, as families outside the guardrails waved Israeli flags and cheered. At 68th Street, one of those sidelined spectators leaned against a rail and offered his support for Weiner.

“Anyone who would say that he didn’t back up his work on TV with work in the committee is a baldfaced liar,” said Charles B. Rangel (D), the once-mighty dean of the New York congressional delegation whom the House censured last year for ethics violations.

“I worked with him. He’s a good member of Congress. Period.”