WASHINGTON — Wacky lefty influencer and Kennedy family scion Jack Schlossberg lunched his bid for Congress Wednesday — declaring that he’s going after outgoing Democratic Rep. Jerrold Nadler’s seat.

But if he thinks he can waltz into New York’s 12th Congressional District — which encompasses a huge chunk of Manhattan — he’s doesn’t know jack, say political watchers.

“First of all, the Kennedy name is not magic any longer,” Leamer, author of the new book “Lady’s Man: The Careless Life of John F. Kennedy,” told The Post.

Schlossberg, 32, the grandson of John F. Kennedy who is renowned for his online trolling and incendiary screeds against Republicans, leaned on the Kennedy name with his campaign launch.

He also included a photo on his campaign website that looks remarkably similar to a famous pic of his late uncle, John F. Kennedy Jr.

“He’s going to have to win this on his own,” Leamer added. “The second thing is, his mother ran for the Senate, or started to run for the Senate, and when she got out of her private life and she saw the questions journalists asked … she backed out.”

In 2008, Schlossberg’s mother, Caroline Kennedy, now 67, toyed with a run for a Senate seat held by Hillary Clinton, but ultimately backed off weeks later.

Nadler, 78, dissed the prospect of a Schlossberg run back in September.

“Well, there’s nothing particularly good or bad about a Kennedy holding my seat. But the Kennedy, unlike Schlossberg, should be somebody with a record of public service, a record of public accomplishment, and he doesn’t have one,” Nadler told CNN at the time.

“He certainly is not going to be a major candidate. There will be major candidates,” said Nadler, whose office declined further comment Wednesday.

Former Rep. Carolyn Maloney (D-NY), however, told the Post: “The Kennedy name has magic.”

Maloney, who ran against Nadler in the 2022 midterms after redistricting put them on a collision course, revealed that Schlossberg asked to meet her last month.

“He’s a very purposeful, dedicated man,” Maloney said. “The Kennedy clan has contributed greatly to this country. But there are other candidates who have magic, too.”

Schlossberg has made a name for himself online, having made lewd jokes about having a child with Vice President JD Vance’s wife, Usha, and frequently raged against his cousin, Health and Human Services Secretary Robert F. Kennedy Jr. 

The Kennedy scion even bashed RFK Jr. as “dangerous” and a “rabid dog” during a Wednesday interview on MSNBC. 

Those antics have given some Democrats pause. 

“He’s either mentally ill or a provocateur,” said lawyer Alan Dershowitz, who lives in the 12th District, but does not vote there. “I don’t know whether his mishegas– his craziness — comes from a desire to sell a podcast or comes from within.”

Dershowitz, who briefly worked for Schlossberg’s uncle, the late Sen. Ted Kennedy, had threatened to sue Schlossberg for defamation after he accused Dershowitz of killing his wife in an Instagram post earlier this year.

“He’s a nutcase and the idea that he would be running for Congress because of who his mother and his grandfather are, tells us something not very good about the electorate,” chided Dershowitz, an emeritus professor at Harvard Law School.

Some Democratic operatives believe Schlossberg may be formidable despite his hot-headedness. 

“I expect he’ll have the resources to run a credible campaign,” New York state Sen. James Skoufi said. “Whether restless voters are in the mood to elect a candidate who will inevitably lean into legacy Democratic politics is another story.”

“The Democratic electorate is increasingly looking for candidates who will break up the status quo at all levels of government – not just federal,” Monica Venzke, a self-described Schlossberg “apologist” who runs the X account Boyfriends We Deserve, told the Post that “Kennedy-stalgia” will certainly play a role in the scion’s run, even as his social media presence includes some “crazy s–t” that could divide older and younger Democratic voters.

“I do think that his silliness will be his strength,” Venzke said. “A lot of Democrats should take notes on using the internet and podcasts and social media and all that stuff in a way that Republicans are doing better than us now, we have to catch up.”

“He does all these, like, rage-baiting, silly tweets where he said that his grandma wasn’t as hot as Usha Vance and he pretended that he was Justin Baldoni’s lawyer, which wasn’t true,” she continued. “Schlossberg says crazy s— and then everyone’s like, ‘What is he talking about?'”

Privately, Schlossberg’s mother has been “seriously frightened” by his foray into the congressional race, nervous that the “political world has become too dangerous,” a source previously told The Post.

Another Democratic source with ties to many in the 12th Congressional District race mused that “Schlossberg has the chutzpah and the political charisma to part the seas of the New York political establishment like no one has in a long, long time.”

“Schlossberg, the genuine outsider, is tethered to an aura that should not be underestimated. He is modern art for politics,” that source added. “There’s going to be a long line to watch him paint. This is now a national race and Donald Trump should be very worried because that’s good for Democrats across the board.”

Many of those Schlossberg hopes to represent were not impressed with his behavior. 

“RFK is related and look how awful he is,” said Robin, an Upper West Side resident. “Any TikTok star is not serious about our country and our needs.” 

Kennedy Moore, 63, who works in the Upper West Side but lives in Queens, blasted Schlossberg as a “jackass.”

“Quite frankly, it’s a little disturbing that he goes on these rants, so I think we can take him off the vote meter for this Kennedy,” he said, pointing at himself. “We’d like someone who is not immature.”

Upper West Side resident Christine Wood, 43, brushed off Schlossberg’s unhinged posts but said she won’t vote for him after watching his campaign release video on Wednesday morning. 

“I think everyone has completely lost their minds on every f—ing side.”