Attorney general candidate Paul Zukerberg, center, gets a voter signature from John VanMeter in Adams Morgan in his bid to qualify for the D.C. ballot. At left is supporter Scott Simpson. (Yue Wu/The Washington Post)

Paul Zukerberg stands on a Mount Pleasant street corner, holding a clipboard. He is squat, unshaven and wears frayed jeans and a dirty sport coat. Patrons of the nearby farmers market blow right past.

“Excuse me, miss, are you a D.C. voter?” he squawks in his Paterson, N.J., patois.

He doesn’t look it this Saturday morning, but Zukerberg is, in fact, a candidate for D.C. attorney general — the first ever — and is seeking to qualify for the ballot. More than that, he is the main reason there will be an attorney general election this year, after successfully taking the District government to court over a delay to an election mandated by city voters in 2010.

“His emergence, his willingness to take this on got this election back on track,” said Walter Smith, the executive director of the DC Appleseed Center for Law and Justice, a think tank that has advocated for converting the attorney general post, long appointed by the mayor, to an elected office.

Now Zukerberg, a loquacious 56-year-old father of two, is tasked with pivoting from a grueling court battle to a grueling campaign for a post meant to serve as an independent check-and-balance on the mayor and the D.C. Council. With Zukerberg’s court victory, the race has attracted at least one pillar of the Washington legal establishment, defense attorney Mark H. Tuohey of Brown Rudnick, and potentially several others.

Paul Zuckerberg poses for a portrait on June 26, 2014, in Washington, D.C. (Yue Wu/The Washington Post)

While he has a head start, Zukerberg is still trying to capi­tal­ize on his advantage. His campaign is running on a shoestring out of the Adams Morgan townhouse that hosts his law practice. He’s still wearing the same ill-fitting, off-the-rack suits. And he’s got 3,000 voter signatures to collect before qualifying for the ballot.

What Zukerberg does have is persistence. This is a guy who met his wife of 18 years while traveling in Israel and then devoted 18 months of letters and made an impulse trip to her native Lithuania before she agreed to marry him.

When the D.C. Council voted last fall to delay the attorney general election from 2014 to 2018 — and potentially much longer — he did not throw up his hands. “I thought, I’ll just file a quick lawsuit; it’ll be a slam dunk, like all my cases,” he joked.

Not so much. The case bounced between federal and local courts for months. Zukerberg was forced to declare his candidacy and collect petitions for a primary election that might never happen. And then, when a Superior Court judge ruled against him, it didn’t.

But lawyer Gary Thompson, who took over the case pro bono after Zukerberg asked Smith for help, said an appeal was never in doubt. “I just love an underdog, and that’s what Paul is,” he said.

The D.C. Court of Appeals ruled this month that the council had no power to delay the election. Although some loose ends remain, Zukerberg won final victory Tuesday when the court declined to revisit its decision and the D.C. Council voted to set the election for Nov. 4.

“He took on the council, he took on the current attorney general, and he won,” said council member Tommy Wells (D-Ward 6). “I think that the voters in the District owe him a debt.”

Supporter Scott Simpson, left, helps Paul Zuckerberg with signs at his law office in Washington, D.C. (Yue Wu/The Washington Post)

That Zukerberg might now have a legitimate claim to be D.C. attorney general is an unlikely outcome for the son of a New Jersey band­leader — known, according to an obituary in the Bergen County Record, as “the bar mitzvah king.” The younger Zukerberg sold Italian marble until he fled to law school and then spent his career in a nitty-gritty legal practice, a jack-of-all-trades handling everything from wills to torts but mainly criminal defense.

He co-defended Chander “Bobby” Matta, an Arlington man charged with (and convicted of, after Zukerberg withdrew) strangling three prostitutes. He has defended a Prince William County teacher who pleaded guilty to possessing child pornography and the proprietor of an online matchmaking site who was sued after one of its clients was badly abused by her match.

Other clients were more sympathetic: He represented employees of a city-owned nursing home who were stiffed by its private operator; a dog owner whose pet was spayed without authorization after the Washington Humane Society picked it up; and the family of a 10-year-old boy who was badly injured after falling off a diving board at a D.C. public pool.

In one of Zukerberg’s most consequential ­cases, he defended a D.C. police detective who was accused of distributing cocaine and taking bribes to search law enforcement data­bases. A jury rejected the cocaine ­charges, and a U.S. appeals court eventually tossed out the rest of the case in a landmark decision that continues to define the limits of the federal bribery statute.

But it’s for his marijuana cases­ that Zukerberg has made his name — a reputation, in fact, he cultivates. One of his Web sites is DC Marijuana Lawyer Blog. He sits on a legal advisory board for NORML, the National Organization for the Reform of Marijuana Laws. And marijuana decriminalization was, by far, the widest plank in his unsuccessful 2013 run for an at-large council seat.

The decriminalization law that passed this year — in part, due to Zukerberg’s advocacy — stands to cut deeply into his livelihood. “I could have cruised through the next nine years representing poor people who happened to get caught with marijuana,” he said. “But I’m happier inside knowing I made some positive change, even though I may have to brush up on real estate law.”

“Or,” he adds, “I could actually get elected. That would be ideal.”

His interest in marijuana, he says, is grounded in civil rights — not in his financial bottom line (pot cases are half his business) or his recreational interests. At his election-night party last year, he cracks, one reporter told him that he expected a smoke-filled “bacchanalia” when, in fact, “it was a bunch of 50-year-olds talking about their kids’ homework.”

In his conference room — stocked with Heineken and pinot noir but no Purple Kush — he plops a sheaf of papers on the table: charging documents from a recent marijuana possession case. As he describes the circumstances, he gets worked up to the point that he can’t quite form complete sentences: “Three officers . . . suspect information, then another long narrative . . . one hand-rolled cigarette is going to be sent to the DEA laboratory . . . all of this is done for one joint. . . . Just to give you an idea how ridiculous.”

He criticizes U.S. Attorney Ronald C. Machen Jr. for continuing to prosecute marijuana possession cases with a decriminalization law set to take effect within weeks. William Miller, a Machen spokesman, declined to comment on Zukerberg’s critique.

Zukerberg is also critical of Irvin B. Nathan, the current, appointed attorney general — not only for fighting Zukerberg’s lawsuit at every step but also for his office’s approach to juvenile justice, contract and tax disputes, and its objections to Machen’s requests for documents potentially connected to the corruption investigation into the 2010 campaign of Mayor Vincent C. Gray (D).

Nathan declined to comment through a spokesman, but in an April letter published by the Huffington Post, he suggested that Zukerberg has tended to “distort and misstate facts” and “is not worthy of the position he seeks.”

Winning will not be easy. His council run ended in a fifth-place finish with 2 percent of the vote, and his campaign is only now starting to gear up. But his most formidable obstacle might be expectations.

For most of the past 25 years, the appointed office has been mainly held by men who have passed through Ivy League law schools and prestigious corporate firms — guys such as John A. Payton (Harvard; Wilmer, Cutler & Pickering), John M. Ferren (Harvard; Hogan & Hartson), Charles F.C. Ruff (Columbia; Covington & Burling), Peter J. Nickles (Harvard; Covington & Burling) and Nathan (Columbia; Arnold & Porter).

Tuohey is a former federal prosecutor turned white-collar defender, and two other litigators with similar pedigrees — insurance specialist Lorie S. Masters of Perkins Coie and white-collar defender Karl A. Racine of Venable — are also considering entering the race.

Zukerberg (American University; Zukerberg Law Center) is not cut from Brooks Brothers cloth, and he’s hoping that will work to his advantage.

“We need somebody who’s going to check their privilege at the door,” he said. “Maybe people have to change their expectations if they want to change the system. If they keep bringing in these big-corporate, big-government types, they’re going to get the same system they have now.”

Thompson (Georgetown; Reed Smith) said he hasn’t decided who he’ll be voting for, but he said Zukerberg starts with one clear advantage.

“He’s the guy who made it possible,” Thompson said. “He took the time. He had the fortitude to protect the vote. Whoever else who is in the race is going to have to explain: What were you doing?”