President-elect Donald Trump's influential son-in-law Jared Kushner will join him in the White House as a senior adviser, transition officials said on Monday.
The appointment puts the young real estate executive in position to exert broad sway over both domestic and foreign policy, particularly Middle East issues and trade negotiations.
Mr Trump has come to rely heavily on Mr Kushner, who is married to the president-elect's daughter Ivanka.
Since the election, Mr Kushner has been one of the transition team's main liaisons to foreign governments, communicating with Israeli officials and meeting last week with Britain's foreign minister Boris Johnson. He has also met with congressional leaders and helped interview Cabinet candidates.
However his eligibility could still be challenged though Mr Kushner's lawyer Jamie Gorelick argued that a 1967 law meant to bar government officials from hiring relatives does not apply to the West Wing. She cited a later congressional measure to allow the president "unfettered" and "sweeping" authority in hiring staff.
Mr Kushner, who will not be taking a salary, will resign as CEO of his family's real estate company and as publisher of the New York Observer, as well as divest "substantial assets," Ms Gorelick said.
She said Mr Kushner will recuse himself "from particular matters that would have a direct and predictable effect on his remaining financial interests".
Ivanka Trump, who also played a significant role advising her father during the presidential campaign, will not be taking a formal White House position, transition officials said. She is the mother of three young children, and her immediate plans are focusing on her family's move from New York to Washington, though officials said her role could change in the future.
Officials also said Ivanka would be leaving her executive roles at the Trump Organisation - her father's real estate company - and her own fashion brands.
The anti-nepotism law has appeared to be the main obstacle to both Mr Kushner and Ivanka joining the White House. In arguing that the measure did not apply to the West Wing, Ms Gorelick cited an opinion from two federal court judges in a 1993 case involving Hillary Clinton's work on her husband's health care law.
Norman Eisen, who served as President Barack Obama's government ethics lawyer, said there is a "murky legal landscape" regarding the anti-nepotism law. But he said Mr Kushner appeared to be taking the proper steps regarding the ethics and disclosure requirements for federal employees.
Mr Kushner, who turns 36 on Tuesday, emerged as one of Mr Trump's most powerful campaign advisers during his father-in-law's presidential bid. Soft-spoken and press shy, he was deeply involved in the campaign's digital efforts and was usually at Mr Trump's side during the election's closing weeks.
He has continued to be a commanding presence during the transition, working alongside incoming White House chief of staff Reince Priebus and senior adviser Steve Bannon.
Meanwhile, Mr Trump has said he expects all of his choices for Cabinet positions to be approved by the Senate.
He made the prediction as he briefly addressed reporters in Trump Tower in New York City, appearing alongside Chinese billionaire Jack Ma.
Senate confirmation hearings begin on Tuesday, starting with Mr Trump's choice for attorney general, Jeff Sessions.
Mr Trump described Mr Sessions on Monday as "a high-quality man", adding: "He's going to do great."
He said all of his nominees are "at the highest level, and added: "I think they'll all pass."