United Auto Workers is looking to get a leg up in its negotiations with General Motors — by going directly after the company’s charismatic boss.

Brass at the labor union — whose strike has idled 46,000 workers at 34 plants nationwide — has held high-level talks this week about staging a “no-confidence” vote on chief executive Mary Barra, The Post has learned.

Sources briefed on the talks cautioned that no vote is imminent, and the UAW is bracing for negotiations — which on Wednesday had entered their 17th day — to drag into next week.

Strictly speaking, a no-confidence vote by the UAW wouldn’t carry any force with GM or its board of directors, which is chaired by Barra.

Still, some members see it as an effective way to put pressure on 57-year-old Barra, who has burnished a reputation on Wall Street as a tough negotiator, according to sources briefed on the union’s thinking.

Specifically, some in UAW’s leadership believe that it was Barra who personally decided to backtrack on a decision to yank health care coverage for striking workers.

Some union brass believe that Barra flip-flopped for fear of bad publicity after the UAW had sought to make her personally responsible for the hard-knuckle move, according to sources.

“Internally, there was this theory to stop looking at GM as a corporation and start looking at Mary, because they got the win on health care. And it was her decision,” one source directly familiar with the negotiations told The Post.

Unlike a no-confidence vote by a company’s shareholders, any vote by the workers would be largely “symbolic” since workers don’t have a significant ownership stake in the company, Jon Shelton, an associate professor at University of Wisconsin – Green Bay, told The Post.

“I can’t imagine a scenario where there would be anything binding about it besides another way to draw attention to the leadership of the company,” said Shelton, author of the 2017 book “Teacher Strike! Public Education and the Making of a New American Political Order.”

“I have to say, a no-confidence vote in a CEO is not used as a tactic too often,” Shelton added.

UAW workers have been on strike since Sept. 16 over a dispute with the Michigan automaker over health care and job security. The work stoppage has caused pain on both sides.

Analysts estimate GM has suffered losses of more than $1 billion. Starting this week, meanwhile, workers have begun to rely on weekly strike paychecks of $250 — on average, about a fifth of what they had been taking home.

A spokesman for the UAW declined to comment. A GM spokesman didn’t immediately return a request for comment.