President Trump’s special envoy for Middle East peace, Jason Greenblatt, will leave the administration, according to a senior Trump official, raising new questions about a long-delayed plan to resolve the Israel-Palestinian conflict.

Trump had warm words for Greenblatt on Twitter. “Jason has been a loyal and great friend and fantastic lawyer,” Trump wrote, praising his “dedication to Israel.”

“It has been the honor of a lifetime to have worked in the White House for over two and a half years under the leadership of President Trump,” Greenblatt said in a statement. “I am incredibly grateful to have been part of a team that drafted a vision for peace. This vision has the potential to vastly improve the lives of millions of Israelis, Palestinians and others in the region.”

Kushner added in a statement that  Greenblatt “has done a tremendous job leading the efforts to develop an economic and political vision for a long sought after peace in the Middle East,” saying he would remain a “close friend and partner.”

After Greenblatt’s departure, Avi Berkowitz, an adviser to Kushner, will become “more involved in the process,” the Trump official said. So will Brian Hook, the State Department’s special representative for Iran.

Read more at The New York Times.