Russert's precise and relentless style of questioning made him a highly valued if fearsome interviewer who was respected on both sides of the political divide.

Hearing of his death, Barack Obama commented that "there wasn't a better interviewer in television", while John McCain hailed Russert as the "pre-eminent journalist of his generation".

Timothy John Russert was born in Buffalo, New York State in 1950 and graduated from John Carroll University, Ohio, in 1972 with a degree in political science before moving to Cleveland-Marshall College of Law.

After leaving law school in 1976, Russert worked on the successful senatorial campaign of New York Democrat Daniel Moynihan, staying on as his chief of staff for a further five years.

He then moved to work for Mario Cuomo, also a New York Democrat, and was counsellor in the Governor's Albany office until 1984, when he left to join the Washington Bureau of the NBC television network.

There, he forged a reputation as a meticulous, knowledgable journalist and his first major scoop was arranging Pope John Paul II's first interview on American television in 1985.

By 1988, he had been promoted to bureau chief, and three years later, took over the failing Sunday morning program Meet the Press, which he transformed into American television's No 1 flagship political news show.

By the time of his death, NBC had, in a highly unusual move for the US media world, signed Russert to an 11-year contract.

The face of NBC's election night coverage, Russert was famous for frantically scribbling figures on to a whiteboard as he calculated possible outcomes of votes.

He was noted for his prescient predictions, accurately forecasting that Florida would be the key state in the 2000 election and Ohio would play the same role in 2004.

In 2007, Russert hit the headlines himself, during the investigation into "Plamegate", a CIA scandal that involved I. Lewis "Scooter" Libby, a former chief of staff to the Vice-President Dick Cheney.

Libby was charged with obstructing a federal investigation into who had leaked the identity of Valerie Plame, a CIA operative, after her husband had criticised the Bush administration.

Libby testified that he had learnt of Plame's identity from Russert, but Russert denied that they had ever discussed it. The jury believed him and convicted Libby.

Russert was the author of two bestselling books. The many awards he received for his work included an Emmy in 2005 for his coverage of Ronald Reagan's funeral. This year Time magazine named Russert one of the world's 100 most influential people.

He is survived by his wife and son.