“Zero” Senate Republicans are privately opposing Pete Hegseth’s confirmation, sources told The Post on Wednesday, as the defense secretary-designee was making the rounds on Capitol Hill and defiantly proclaiming he will “never back down” in the face of widespread allegations of past misconduct.

“There are zero ‘nos’ right now,” one GOP source familiar with the matter said, ripping smears against the former Army combat infantryman in the press as “BS.”

At least six Republicans, however, have expressed some reservations about President-elect Donald Trump’s nominee, NBC News reported Tuesday, as claims of binge drinking, sexual impropriety and financial mismanagement during his tenure as leader of a veterans advocacy group pile up.

Publicly, they have been keeping their powder dry on Hegseth’s nomination as they wait for additional evidence and information to come forward.

“I appreciate Pete Hegseth’s service to our country, something we both share. Today, as part of the confirmation process, we had a frank and thorough conversation,” Sen. Joni Ernst (R-Iowa) posted on X after meeting with him.

“I’m going to let the process work itself out. I’ve known Pete for a number of years and I haven’t had a chance to talk to him since he was nominated,” Sen. John Cornyn (R-Texas) told reporters.

“The articles I’ve read, yeah, some of them are concerning. I don’t know if it’s true or not. But he’ll go through the process and we’ll see what happens,” Sen. Lindsey Graham (R-SC), a prominent GOP foreign policy luminary and key Trump ally, said.

Moderate Sen. Lisa Murkowski (R-Alaska) told reporters,“I would like to hear from him about many of the allegations that you all have been reporting.”

Fellow potential swing vote, Sen. Susan Collins (R-Maine) has indicated she is waiting to see what comes out of an FBI background check and a public hearing.

“For every anonymous ‘source’ making an unfounded claim about Hegseth, there are twice as many colleagues and former colleagues who are putting their names publicly on record to refute the defamatory, meritless slander,” another Senate Republican aide told The Post.

“The swamp is just scared of the DOD shakeup that’s coming,” the aide said. “Hegseth should have a hearing, like any other nominee, where he can answer any outstanding questions.”

Only four Republicans would have to vote against him to tank the confirmation.

On Wednesday, Hegseth met with soon-to-be Senate Majority Leader John Thune (R-SD), incoming Senate Armed Services Committee Chairman Roger Wicker (R-Miss.) and Sen. Joni Ernst (R-Iowa), an Army veteran herself who has voted down past political appointees accused of sexual misconduct.

Trump, 78, tapped the 44-year-old vet of the Iraq and Afghanistan wars after being impressed by his book “The War on Warriors,” which was published earlier this year and denounced so-called “woke” initiatives at the Pentagon that have alienated fighting-age males and kept them from enlisting.

“I had a call with the president-elect this morning. He said, ‘Keep going, keep fighting,'” Hegseth told reporters, which a Trump spokeswoman later confirmed to The Post.

“Why would I back down? I’ve always been a fighter. I’m here for the fighters. This is personal & passionate.”

“I’m doing this for the warfighters, not the warmongers,” he also defiantly proclaimed on X ahead of his Hill meetings. “The Left is afraid of disrupters and change agents. They are afraid of [Trump] — and me. So they smear w/ fake, anonymous sources & BS stories. They don’t want truth.”

“Our warriors never back down, & neither will I,” the former Fox News personality added.

Anonymous sources from Hegseth’s past have come forward detailing his alleged problems with drinking, inappropriate sexual advances and fiscally irresponsible tenure as the former head of both Concerned Veterans for America and Veterans for Freedom.

Unnamed former Fox News employees have also accused their ex-colleague of drinking on the job — while others went on the record in X posts to defend his reputation.

“I have routinely sat on the couch with @PeteHegseth for 8 years,” said Fox medical contributor Nicole Saphier. “Not once did I suspect he had consumed anything other than an egg sandwich and coffee before going on air.

“Running a hit piece on a man that’s solely based on anonymous sources is cowardly and isn’t journalism,” added former Fox alum Breanna Morello. “I’m willing to go on the record regarding Pete Hegseth.”

“As a former Fox booking producer, I’ve never heard a negative remark about Hegseth — until now,” Morello added, sharing a letter she is firing off to every US senator denying the allegations of the Trump pick’s purported drinking problem.

Hegseth’s lawyer, Tim Parlatore, and past colleagues at CVA have also strenuously denied all allegations.

Additional reporting by Ryan King.