"Pete is doing very well," Trump said on his Truth Social platform, in his first public comment on the matter since Hegseth began a round of visits seeking Senate support.

In his post, the billionaire Republican called Hegseth "a WINNER," adding "there is nothing that can be done to change that!!!"

Later, in excerpts released by NBC News of an interview set to air Sunday, Trump repeated his confidence in Hegseth.

"I mean, people were a little bit concerned," Trump said of the headwinds on Capitol Hill. "But he loves the military and I think people are starting to see it."

Amid reports the Hegseth nomination was in peril, Trump seemed intent on shoring up Republican support for the 44-year-old military veteran as his pick to head a department with three million employees and a defense budget surpassing $800 billion.

Top presidential nominations require US Senate confirmation. According to NBC News, as many as six Republican senators are lining up against Hegseth -- enough to scupper his nomination in a chamber where Republicans will hold a slim 53-47 majority when the new Congress is sworn in next month.

Since his nomination, Hegseth has been busy visiting senators, especially those thought to be wavering, to lobby for support.

"We're going to earn those votes," he said Thursday in the US Capitol.

And on Friday he thanked Trump for his continued support, saying on X: "Like you, we will never back down."

Just days after Hegseth's nomination was announced, accusations emerged of a sexual aggression dating from a 2017 encounter in California.

But no complaint was filed at the time, and Hegseth -- a former National Guard officer who served in both Iraq and Afghanistan -- has denied any non-consenting relationship.

But doubts grew after the New York Times reported that Hegseth's own mother in 2018 had said in an email to him that he was an "abuser of women" and lacked character.

Penelope Hegseth later appeared on Fox News, the conservative channel where her son worked until last month as a commentator, to say the email had been written "in haste" during his divorce.

The New Yorker magazine then reported Hegseth had resigned as head of two veterans' groups following accusations of sexual aggression, excessive drinking and financial mismanagement.

Trump himself is known to not drink. Asked by NBC if he was concerned his Pentagon pick had struggled with drinking in the past, as people who have worked with Hegseth reportedly have said, the incoming commander-in-chief downplayed the issue.

"I've spoken to people that know him very well and they say he does not have a drinking problem," Trump responded.

The president-elect has already seen one nominee forced out: former congressman Matt Gaetz withdrew as Trump's choice for US attorney general following accusations of sexual relations with a minor.

Gaetz has denied wrongdoing.