NEW YORK (AP) — Robert B. Barnett, a powerhouse Washington attorney who became a fixture in the political and publishing worlds as the literary representative for Barack and Michelle Obama, Bill and Hillary Clinton and dozens of other leaders, has died at age 79.

One of Barnett’s partners at Williams & Connolly, Michael F. O’Connor, told The Associated Press that he died Thursday night at Sibley Memorial Hospital of an “undisclosed illness.” Additional details were not immediately available.

“He was a dear friend, a trusted advisor, and a wise, faithful, and steadfast guide to the publishing and entertainment worlds,” the Clintons said in a statement Friday.

A stocky, raspy-voiced man with tortoiseshell glasses, antique cuff links and a knack for being both forthright and discrete, Bob Barnett embodied an era when it was possible to work freely with both Democrats and Republicans, when politics could stop at the edge of a good book deal. He was a longtime Democrat, working on Jimmy Carter’s 1976 campaign and helping Bill Clinton and other candidates in debate preparation. But he would broker contracts for such a wide range of political figures that he liked to joke that should his clients all gather in one room the result would be “World War III.”

He was a partner at the high-end Williams & Connolly, and for more than 20 years no one approached his stature as an intermediary between the Washington elite and New York publishers. From the early 1990s through the end of the Obama administration, in 2017, Barnett represented three consecutive presidents and first ladies — the Clintons, George W. and Laura Bush and the Obamas — and much of the remaining A-list political players, from Ted Kennedy and Mitch McConnell to Dick Cheney and Alan Greenspan, from Paul Ryan and Donald Rumsfeld to Al Franken and Elizabeth Warren.