Dale L. Bumpers, a liberal governor and four-term Democratic senator from Arkansas who came out of retirement in 1999 to make a passionate closing argument defending President Bill Clinton against removal from office in a Senate trial, died on Friday at his home in Little Rock, Ark. He was 90.

His death was confirmed by his granddaughter Linn Bumpers.

Mr. Bumpers was part of a generation of moderate Southern Democrats, among them President Jimmy Carter, who emerged in the late 1960s and the ’70s. He always said his proudest achievement had come early in his career when, as a small-town lawyer in the 1950s, he guided his native Charleston, Ark., to become the first community of the former Confederacy to integrate its public schools.

But he is remembered more for what he did in the twilight of his career.

Three weeks after retiring from the Senate, he returned on Jan. 21, 1999, to speak to his former colleagues on behalf of Mr. Clinton, a fellow former governor of Arkansas. The House had charged the president with perjury and obstruction of justice for lying under oath about his sexual affair with a White House intern, Monica Lewinsky.

For the Senate trial, Mr. Bumpers was called on to deliver the closing argument for the defense. Before a rapt chamber, he was by turns folksy and self-deprecating, intense and scornful, challenging the House prosecutors who had brought the case to the Senate.