Jared Kushner, the Jewish son-in-law of President-elect Donald Trump, may play a very key role in the Trump administration, the Wall Street Journal reported on Wednesday.

Trump and Kushner, who is the husband of Trump’s daughter Ivanka and the father of the president-elect’s three Jewish grandchildren, enjoy a close personal and professional relationship; despite his own work as a real estate developer and publisher, Kushner campaigned with Trump and frequently acted as advisor to him on the trail. He was reported to be involved in nearly every aspect of his father-in-law’s campaign.

According to WSJ, Trump’s newly-appointed chief of staff, Reince Priebus, and senior counselor, Stephen Bannon, are encouraging Kushner to become a formal adviser or “special counselor” to his father-in-law once he takes office.

Anti-nepotism laws prevent presidents from appointing family members to any official positions within their administrations, so Kushner’s potential post is unclear but likely to take the form of an unpaid advisor role.

Should he choose to accept a position in the White House under Trump, Kushner would have to give up control of his considerable real estate empire, ceding it to a blind trust in which he would have no hand. He would not be able to receive any income from his real estate or media assets.

He would also be unavailable to Trump on Friday evenings and Saturdays, the Jewish Sabbath, which he observes strictly. He and Ivanka, who underwent a rigorous conversion process before marrying, consider themselves Orthodox and are raising their three young children in the Jewish faith.