Tim Russert

Tim Russert, 58, the longtime host of NBC's "Meet the Press" and the network's Washington bureau chief, collapsed at work and died of an apparent heart attack. (Alex Wong / Getty Images)

New York

Tim Russert, the longest-serving moderator of NBC's "Meet the Press" and the lion of the Washington press corps, died of a sudden heart attack Friday.

He was 58.

Russert had returned early from a family trip to Italy and was working at NBC's Washington bureau, recording voice-overs for Sunday's show, when he collapsed Friday afternoon. His wife, Maureen Orth, a writer for Vanity Fair, and their son, Luke, were still in Italy, where they had been celebrating Luke's graduation from Boston College.

"This news division will not be the same without his strong, clear voice," longtime NBC anchor Tom Brokaw said on MSNBC as he reported the news in a special report. "He will be missed -- as he was loved -- greatly."

"We cannot believe that he's gone, that we've lost his voice and that the country has lost this preeminent journalist," he added.

Russert's physician, Michael A. Newman, told MSNBC on Friday night that cholesterol plaque ruptured in an artery, causing sudden coronary thrombosis. An autopsy also revealed that Russert had an enlarged heart.

Shellshocked NBC News employees struggled with their emotions as they covered the death of the veteran political journalist, who had been a near-ubiquitous presence on MSNBC this year as he reported on the 2008 presidential campaign.

Speaking on MSNBC from Bagram Air Base in Afghanistan, where he is on assignment, anchor Brian Williams described Russert's death as "an unfathomable loss."

President Bush released a statement calling Russert "an institution," and condolences poured in from across the political establishment, over which the newsman exerted huge influence. As NBC News' Washington bureau chief, Russert shaped the network's political coverage, and his Sunday morning talk show helped frame the agenda for the coming week's news cycle.

His pronouncement last month that Sen. Barack Obama of Illinois would be the Democratic nominee heralded the end of the primary race, much to the dismay of the campaign of Sen. Hillary Rodham Clinton of New York.

On “Meet the Press,” which he had moderated since December 1991, Russert drew powerful guests who subjected themselves to his probing, as well as his practice of forcing them to confront their past statements, displayed on-screen.

"For almost a generation, he became the single most authoritative commentator on politics -- an accomplishment that will be hard for anyone to match any time soon," said Tom Goldstein, a journalism professor at UC Berkeley who knew Russert when they were both aides to New York politicians nearly 30 years ago.

On Sunday, Brokaw will host a special edition of "Meet the Press" that will serve as a retrospective of Russert's life.

Russert was an unlikely check on the politically powerful: the son of a sanitation worker who grew up in working-class Buffalo, N.Y., the first of his family to get a college degree.

"He didn't look like your average anchorman," CNN anchor Wolf Blitzer said. "He didn't have the hair or the looks. He was just a smart guy, and he cut through all the b.s."

Despite his encyclopedic knowledge of political history, Russert had an accessible, everyman approach on the air, famously scribbling "Florida, Florida, Florida" on a whiteboard early during the 2000 election night.

Friends said Russert was nearly giddy about covering this year's presidential race and its historic dimensions, working strenuous hours to keep up with the flood of news.

"I have never seen Tim more excited than he was about this campaign," said CBS' Bob Schieffer. "He just fed on it."