WASHINGTON — Jared Kushner, the son-in-law of President-elect Donald Trump and one of his closest confidants, will join the White House as a senior adviser to the president, Trump revealed Monday.

A lawyer assisting the family said that Kushner’s wife, Ivanka Trump, will not immediately take on a formal role.

Kushner, who will not take a salary, is expected to have a broad portfolio that includes government operations, trade deals, and Middle East policy, according to a member of Trump’s transition team. In a statement, the transition office said Kushner would work closely with White House Chief of Staff Reince Priebus and chief strategist Stephen Bannon to execute Trump’s agenda.

Trump relied heavily on Kushner’s advice during the campaign, and his move to the White House was expected. But ethics experts have raised questions about whether Kushner’s role in the new administration will violate a federal antinepotism law and about how he will separate himself from his real estate business to avoid conflicts of interest.

Kushner’s attorney, WilmerHale partner Jamie Gorelick, said in an interview Monday that Kushner is prepared to resign from his business and divest substantial assets, including foreign investments, before taking a White House position. But Gorelick, who served as deputy attorney general under President Clinton, said she is confident that the antinepotism statute does not cover Trump’s appointment of Kushner, though she acknowledged that some lawyers take the opposite view.

Ivanka Trump plans to resign from the Trump Organization and step away from her clothing company but will focus — at least in the short term — on settling the family into its home in Washington, a lawyer working with the family said.

Kushner, 35, has run his family’s multibillion-dollar business over the past decade, after his father pleaded guilty to corruption-related charges.

As Trump campaigned for president, Kushner was an adviser and gatekeeper. Kushner, whose family has donated to causes in Israel, including West Bank settlements that have been branded illegal by the United Nations, also played a role as a Middle East policy adviser.

‘‘Jared has been a tremendous asset and trusted adviser throughout the campaign and transition and I am proud to have him in a key leadership role in my administration,’’ Trump said in a statement.

Some ethics experts question whether a Kushner’s appointment would violate the 1967 federal antinepotism statute, which came about after President Kennedy named his brother as attorney general. It forbids public officials from hiring family members in agencies or offices they oversee, and explicitly lists sons-in-law as prohibited employees.

Richard Painter and Norman Eisen, who served as chief White House ethics lawyers under Presidents George W. Bush and Obama, respectively, say they counseled senior White House officials to avoid appointing relatives to West Wing jobs.

But Gorelick said she is confident that the 1967 law does not apply to the White House, which she said is not an agency.

‘‘This is not a close question,’’ Gorelick said, also citing subsequent law, passed in 1978, that she said allows the president to hire White House staffers ‘‘without regard’’ to federal personnel laws, including the antinepotism statute.

‘‘The Justice Department has described this authority as ‘unfettered’ and ‘sweeping,’’’ Gorelick added.

Eisen said in an interview that ‘‘reasonable people may come to different views on this’’ but that he believes Trump’s appointment of Kushner could prompt ‘‘some interesting litigation about whether [the 1967 law] applies or not.’’

Someone who thinks they are negatively impacted by a Kushner decision could bring suit, Eisen said.

The nepotism issue was examined but not fully resolved in a court case in the early 1990s involving Hillary Clinton’s leadership of a health care panel.

In a separate development Monday, Trump predicted that all his Cabinet picks would win Senate confirmation, even as Democrats charged Trump’s team was ignoring standard vetting protocol.

‘‘I think they’ll all pass,’’ Trump said of his would-be Cabinet, describing them as ‘‘all at the highest level.’’

Lawmakers are waiting for the submission of background material from Cabinet picks, including billionaires whose personal financial dealings have not faced public scrutiny.

Material from the Associated Press was used in this report.