NEW YORK (AP) — Jim Lehrer, longtime host of the nightly PBS “NewsHour” whose serious, sober demeanor made him the choice to moderate 11 presidential debates between 1988 and 2012, has died, PBS said Thursday. He was 85.

Lehrer died “peacefully in his sleep,” according to PBS. He had suffered a heart attack in 1983 and more recently, had undergone heart valve surgery in April 2008.

For Lehrer, and for his friend and longtime partner Robert MacNeil, broadcast journalism was a service, with public understanding of events and issues its primary goal.

“We both believed the American people were not as stupid as some of the folks publishing and programming for them believed,” Lehrer wrote in his 1992 memoir, “A Bus of My Own.”

“We were convinced they cared about the significant matters of human events. … And we were certain they could and would hang in there more than 35 seconds for information about those subjects if given a chance.”

Tributes poured in from colleagues and watchers alike, including from Fox News’ Bret Baier, who called Lehrer “an inspiration to a whole generation of political journalists— including this one.” Dan Rather said “few approached their work with more equanimity and integrity than Jim Lehrer.” And Jake Tapper of CNN called Lehrer “a wonderful man and a superb journalist.” House Speaker Nancy Pelosi called him a “champion for truth and transparency.”

Many Americans knew him best for his role as debate moderator. For seven straight presidential elections, he was the sole journalist sitting across from the candidates for the first debate of the general election campaign. In 1996 and 2000, he moderated all of the debates — five of them — and a vice presidential contest to boot.

He told The Associated Press in 2011 that his goal was to probe the candidates’ thinking and avoid “gotcha” questions. He felt his best debate performance was in 2004, with George W. Bush and John Kerry, not because of anything he did, but because the candidates were able to state their positions clearly.

“I didn’t get in the way,” said Lehrer, whose book “Tension City: Inside the Presidential Debates” told stories of his experiences. “Nobody was talking about what I did as a moderator. I didn’t become part of the story.”

He was lured out of retirement for his last debate in 2012 and it may have been a mistake; he received criticism that year for having too light a touch on the proceedings.

The half-hour “Robert MacNeil Report” began on PBS in 1975 with Lehrer as Washington correspondent. The two had already made names for themselves at the then-fledgling network through their work with the National Public Affairs Center for Television and its coverage of the Watergate hearings in 1973.

The nightly news broadcast, later retitled the “MacNeil-Lehrer Report,” became the nation’s first one-hour TV news broadcast in 1983 and was then known as the “MacNeil-Lehrer NewsHour.” After MacNeil bowed out in 1995, it became “The NewsHour with Jim Lehrer.”

“I’m heartbroken at the loss of someone who was central to my professional life, a mentor to me and someone whose friendship I’ve cherished for decades,” said Judy Woodruff, anchor and managing editor of the PBS NewsHour, in a statement.

Politics, international relations, economics, science, even developments in the arts were all given lengthy, detailed coverage in their show.

“When we expanded to the hour, it changed from being a supplement to an alternative,” Lehrer said in 1990. “Now we take the position that if you’re looking for a place to go every 24 hours and find out what’s happened and get some in-depth treatment, we’re the place.”

Lehrer moderated his first presidential debate in 1988 and was a frequent consensus choice for the task in subsequent presidential contests. He likened the job to “walking down the blade of a knife.”

“Anybody who would say it’s just another TV show is a liar or a fool,” he once said. “I know how important it is, but it’s not about me. It’s what the candidates say that matters.”

He also anchored PBS coverage of inaugurations and conventions, dismissing criticism from other TV news organizations that the latter had become too scripted to yield much in the way of real news.

“I think when the major political parties of this country gather together their people and resources in one place to nominate their candidates, that’s important,” he told The Associated Press in 2000. “To me, it’s a non-argument. I don’t see why someone would argue that it wasn’t important.”

Naturally, Lehrer came in for some knocks for being so low-key in the big televised events. After a matchup between George W. Bush and Al Gore in 2000, David Letterman cracked, “Last night was probably the first and only that time Jim Lehrer (was) the most exciting person in the room.”

But the real-life Lehrer — who had a tradition of buying a new tie for good luck before each debate — was more colorful than he might have seemed on PBS.

On the side, he was also a novelist and sometime playwright. His debut novel “Viva Max!” was made into a movie starring Peter Ustinov. He did a whole series of novels about the adventures of an Oklahoma politician known as The One-Eyed Mack.

“Hemingway said this, too: If you paid attention as a reporter, then when the time came to write fiction you’d have something to write about,” Lehrer told The Associated Press in 1991.

“And it turned out I did. And I’ve got all these stories stored up after 30 years in the news business. And they’re just flowing out of me.”

As Lehrer turned 75 in spring 2009, PBS announced that the show would be retitled as “PBS NewsHour” later in the year, with Lehrer pairing up on anchor duties with other show regulars.

He said he approved of the changes, telling The New York Times that having a pair of anchors would “shake things up a bit,” even as all sectors of the news business struggled to meet changing reader and viewer demands.

Lehrer was born in Wichita, Kansas, in 1934, the son of parents who ran a bus line. In addition to titling his memoir “A Bus of My Own,” he collected bus memorabilia — from station signs to a real 1946 Flxible Clipper bus.

After graduation from college in 1956, he served three years in the Marines, later calling the experience so valuable that he thought all young people should take part in national service.

“I had no close calls, no rendezvous with danger, no skirted destinies with death,” he wrote. “What I had was a chance to discover and test myself, physically and emotionally and spiritually, in important, lasting ways.”

He went to work from 1959 to 1970 at The Dallas Morning News and the now-defunct Dallas Times-Herald. Lehrer jumped to television for a Dallas nightly newscast.

Lehrer wrote that it was ironic that the Watergate hearings helped establish the importance of public TV, since President Richard Nixon hated public broadcasting. He also recalled that the lengthy hearings gave him the chance to practice his new craft, and MacNeil, already a veteran, gave him valuable pointers on how to speak on camera clearly and conversationally.

He is survived by his wife, Kate; three daughters: Jamie, Lucy, and Amanda; and six grandchildren.