For Kushner, Criminal Justice Has Been a Personal Issue and a Rare Victory

Meetings with Kim Kardashian West and Kanye West, organized by Mr. Kushner, also helped bring outsize attention to the issue. And above his office door in the West Wing hangs a poster from Mr. West, with the slogan, “Bringing Dignity to Forgotten America,” and signed, “To Jared from your friend Ye.”

On another track, Mr. Kushner worked to win over skeptical Democrats wary of the Trump administration. When Representative Hakeem Jeffries of New York refused invitations to meetings at the White House, Mr. Kushner agreed to meet him on his turf, so he dined with Mr. Jeffries and Representative Cedric L. Richmond of Louisiana in the Members Dining Hall.

He kept them on board by pushing back against Mr. Sessions, who wanted to insert statutes that were deal breakers for Democrats. “There was a constant back-and-forth with Sessions, and Kushner won that battle,” Mr. Jeffries said. “It’s fair to say that if we’re able to get meaningful criminal justice reform over the finish line, it would not have occurred without substantial leadership from Jared Kushner.”

Representative Josh Gottheimer, Democrat of New Jersey, recalled hearing from Mr. Kushner on the issue as early as April 2017.

“Jared called and asked if he could meet with the caucus, and he and Van Jones and Grover Norquist showed up,” Mr. Gottheimer said. “It was a motley crew that came in. I spoke to him regularly over the ensuing months. He was obviously very committed.”

Over Thanksgiving, Mr. Kushner realized that the message had sunk in. He was out of town when he saw that Mr. Trump — without any prodding — wrote on Twitter: “Really good Criminal Justice Reform has a true shot at major bipartisan support. @senatemajldr Mitch McConnell and @SenSchumer have a real chance to do something so badly needed in our country. Already passed, with big vote, in House. Would be a major victory for ALL!”

But the bill still has its detractors. On the right, Senator Tom Cotton, Republican of Arkansas, continues to oppose cutting mandatory minimum sentences for serious crimes and has campaigned to defeat the bill.