Pete Hegseth was sworn in as the defense secretary on Saturday morning by Vice President JD Vance after the Senate narrowly confirmed Mr. Hegseth the night before. The Trump pick survived a bruising struggle with Democrats who decried him as unqualified and unfit to oversee the country’s 1.3 million active duty troops and the Pentagon’s nearly $850 billion budget.
Vice President Vance had to cast a tiebreaking vote to confirm Mr. Hegseth, after three Republicans — Senators Susan Collins of Maine, Lisa Murkowski of Alaska and Mitch McConnell of Kentucky — joined all Democrats in opposition.
The final vote, 51 to 50, was the smallest margin for a defense secretary’s confirmation since the position was created in 1947, according to Senate records.
Mr. Hegseth, a military veteran and a former Fox News host, has vowed to bring his self-described “warrior” ethos to the Defense Department, which he says has been made weak by “woke” generals and diversity programs.
Republican leaders embraced that outlook as they cheered his confirmation.
“Peace through strength is back under President Trump and Pete Hegseth,” Senator Roger Wicker, Republican of Mississippi and the chairman of the armed services panel, said in a statement after Mr. Hegseth’s confirmation, adding: “We cannot wait another minute to rebuild our military might and put the war-fighter first.”
But Democrats, who unanimously opposed Mr. Hegseth’s confirmation, promised to continue their scrutiny of him.
“I am going to watch him like a hawk,” Senator Jack Reed of Rhode Island, the top Democrat on the armed services panel, said in a statement, adding: “I will point out where we disagree. I will demand accountability.”
Mr. Hegseth’s selection by President Trump and the confirmation process were complicated by a claim of sexual assault and accusations of abusive behavior, public drunkenness and fiscal mismanagement of two nonprofit veterans groups.
In a sworn statement submitted to the Senate on Tuesday, a former sister-in-law of Mr. Hegseth’s described him as frequently intoxicated and “abusive” toward his second wife. Mr. Hegseth, 44, has denied the account, along with other allegations that have dogged his nomination.
And on Thursday, the office of Senator Elizabeth Warren, Democrat of Massachusetts, shared written answers to questions she put to Mr. Hegseth, in which he disclosed that he paid $50,000 to a woman who accused him of sexual assault in 2017.
He has said that encounter was consensual, and he was never charged with a crime.
A handful of Republicans had said privately that the new allegations in the affidavit from Danielle Diettrich Hegseth, the former wife of Mr. Hegseth’s brother, were concerning. But in the end, only Ms. Collins, Ms. Murkowski and Mr. McConnell voted with Democrats against his confirmation.
Ms. Hegseth said after the vote that she had submitted her affidavit only because she had been assured that it would sway key votes. “There are many reasons women are reluctant to come forward, by name, and tell the truth about a powerful man like him,” she said. “What happened today will make women who have experienced abuse and mistreatment even less forthcoming.”
None of the three Republicans who voted against confirmation cited the affidavit or the allegations of personal misconduct as a reason for a decision to oppose Mr. Hegseth, though Ms. Murkowski said they “do nothing to quiet my concerns.”
Mr. McConnell stressed that in his estimation, Mr. Hegseth had not demonstrated a sufficient understanding of national security challenges to handle the job of defense secretary, which he called “the most consequential cabinet official in any administration.”
“Effective management of nearly 3 million military and civilian personnel, an annual budget of nearly $1 trillion, and alliances and partnerships around the world is a daily test with staggering consequences,” Mr. McConnell said in a statement explaining his vote. He added: “Mr. Hegseth has failed, as yet, to demonstrate that he will pass this test.”
Opponents of Mr. Hegseth’s confirmation had fervently hoped to win over a fourth Republican, Senator Thom Tillis of North Carolina. Mr. Tillis had pledged to conduct “due diligence” on the allegations against Mr. Hegseth, including those in the affidavit from his former sister-in-law. He appeared to waver, then voted in favor of confirmation.
“Pete has a unique perspective as a veteran of the wars in Iraq and Afghanistan and is unquestionably passionate about modernizing our military and supporting the brave patriots like himself who serve our nation,” he said in a statement explaining his choice. He added that he would “look forward to working with him to rebuild our military and advance President Trump’s peace through strength agenda.”
Nearly all recent defense secretaries have sailed through their final votes. President Joseph R. Biden Jr.’s defense secretary, Lloyd J. Austin III, was confirmed on a 93-to-2 vote. The Senate voted 98 to 1 to confirm Jim Mattis, President Trump’s first Pentagon chief, and 90 to 8 for his successor, Mark Esper.
There have been exceptions. Chuck Hagel, a former Republican senator, won a narrow victory in 2013 despite opposition from 41 members of his own party over his skeptical views on the Iraq war. John G. Tower, the nominee of President George H.W. Bush, was defeated in a 47-to-53 vote in 1989 amid allegations of alcohol abuse and womanizing.
Mr. Hegseth had similar allegations to contend with, but that was a different time and a different Senate.
Mr. Hagel never really recovered from his Senate bruising and resigned under pressure two years into his term. Mr. Mattis resigned after two years in a rebuke of Mr. Trump’s worldviews and treatment of allies, and Mr. Esper was fired by Mr. Trump via a social media post after a year and a half on the job.
Mr. Trump briefly considered dropping Mr. Hegseth amid resistance from senators in both parties. But Mr. Trump dug in. During his confirmation hearing, Mr. Hegseth called the allegations against him “anonymous smears.”
Samantha Hegseth, Mr. Hegseth’s second wife, has said publicly that he never physically abused her. But a Trump transition official informed the leaders of the Armed Services Committee last week that she had told the F.B.I. during a background interview that Mr. Hegseth drank to excess and continues to do so, according to a person with knowledge of the findings.
Senator Jack Reed of Rhode Island, the top Democrat on the armed services panel, who was briefed on the findings, said reporters’ characterizations of the findings were “true and accurate.” Senator Roger Wicker, Republican of Mississippi and the panel’s chairman, who was also briefed, called those characterizations “starkly and factually inaccurate.”
Sharon LaFraniere contributed reporting.
Pete Hegseth’s former sister-in-law, who submitted an affadavit this week accusing him of abusive behavior toward his second wife, issued a statement after the vote. “What happened today will make women who have experienced abuse and mistreatment even less forthcoming because the men involved in the decisions leading to Hegseth’s confirmation have actively perpetuated the mechanisms, including gag orders and fear of retaliation, that keep women silent,” said Danielle Diettrich Hegseth, the ex-wife of Hegseth's brother.
Nearly eight years ago, another Trump administration cabinet secretary barely survived her confirmation vote, advancing only after a vice president’s tiebreaker vote.
That nominee was Betsy DeVos, the wealthy Republican donor who had almost no experience in public education and who was confirmed to lead the Department of Education.
On Feb. 7, 2017, two Republican senators, Susan Collins of Maine and Lisa Murkowski of Alaska, turned against Mr. Trump’s pick for the job and voted against her. But without a third Republican to join their ranks, Ms. Devos was ultimately confirmed on a 51-to-50 vote.
It was the first time a vice president — in this case, Vice President Mike Pence — had been summoned to the Capitol to break a tie on a cabinet nomination.
On Friday, Pete Hegseth became the second person to be confirmed to a cabinet secretary post when Vice President JD Vance cast the deciding vote, ensuring he will be the next defense secretary. Ms. Murkowski and Ms. Collins also voted against him, along with Senator Mitch McConnell, Republican of Kentucky.
Democrats argued that allegations of sexual misconduct, abusive behavior, public drunkenness and fiscal mismanagement of two nonprofit veterans groups made Mr. Hegseth unqualified and unfit to oversee the country’s 1.3 million active duty troops and the Pentagon’s nearly $850 billion budget.
Some Democratic Senators, however, are being more cordial. “Now that he has been confirmed to this position, I sincerely hope we can work together in good faith to ensure the wellbeing of our service members,” Senator Jeanne Shaheen, Democrat of New Hampshire, said in a statement. “It’s critical we put the security of Americans and our nation above all else.”
The criticism of Republicans for falling in line with Trump is pouring in from watchdog organizations and the left. “This confirmation shows that most Republican Senators are willing to rubber-stamp the lowest common denominator from the Trump administration even when it puts everyday Americans in harm’s way. That’s terrifying,” Tony Carrk, the executive director of Accountable.US, a nonprofit watchdog organization.
The last time a cabinet nominee needed the vice president to cast a tiebreaking vote was Betsy DeVos, the wealthy Republican donor who had almost no experience in public education. She was confirmed in 2017 to be Trump’s first education secretary despite two defections from her own party, and only after former Vice President Mike Pence broke the tie.
In a statement, McConnell hit at Hegseth’s lack of strategic credentials as among his reasons for opposing him, saying, “Mr. Hegseth provided no substantial observations on how to defend Taiwan or the Philippines against a Chinese attack, or even whether he believes the United States should do so. He failed, for that matter, to articulate in any detail a strategic vision.”
Because of the narrow margin in the Senate over the previous four years, former Vice President Kamala Harris cast a record number of tie-breaking votes. The current Republican majority, at 53-47, has a little more breathing room but the vice president is geting an early opportunity to fill the presiding officer’s role at a big moment.