Donald Trump finally had a few successful days—the Syria strike, the confirmation of Neil Gorsuch, his apparently successful intervention in the feud between his top advisers. But just as he’s built some momentum, he’s about to face a circumstance that’s thrown him off course in the past.

Monday night marks the beginning of Passover, a Jewish holiday observed by Trump’s senior adviser and son-in-law, Jared Kushner, and his White House assistant and daughter, Ivanka Trump. A White House official said that Kushner will not return to work until Wednesday night.

Kushner, 36, an Orthodox Jew, holds one of the most far-reaching West Wing portfolios in memory. But with all of this on his plate, perhaps his most vital function within the West Wing has been his moderating influence on his father-in-law. As one person close to the family noted to me earlier this year, Kushner observes Shabbat, meaning that from sundown on Friday until sundown on Saturday each week, he does not work or use technology. It just so happens that Trump tends to get himself into trouble on Shabbat, alleging on Twitter during one of those Kushner interregnums that President Barack Obama was a “bad (or sick) guy” who had wiretapped Trump Tower during the election, and signing his first Muslim ban executive order, which prompted worldwide protests and was struck down by federal courts, during another.

“To me, that’s not a coincidence,” the source close to the family told me.

VIDEO: Jared Kushner, Adviser to the President

Trump will be unsupervised by Kushner from Monday night through Wednesday evening.

The White House confirmed that it would be holding a Seder on Monday evening, though a spokesperson did not confirm if either Kushner or the president would be in attendance, noting that the tradition, which started under President Obama, is “still taking shape.”

The Seder is not on the president’s daily schedule. (A staffer from the previous administration told me that President Obama attended the Seder every year, starting on the 2008 campaign trail, when he caught wind of his staffers holding one while they were on the road in Harrisburg, Pennsylvania. The staffer noted that Malia and Sasha Obama would search for the afikomen, a ritual part of the Seder service.)

“Many of our Jewish staff are actually going to be able to spend the holiday with their families,” the Trump spokesperson said. For those who can’t take the time off to go elsewhere, this “will be an opportunity for observant White House staff that can't be with their families to celebrate the holiday among friends.”