Tim Russert, the host of “Meet the Press,” and NBC’s Washington bureau chief, has died. He was 58. Mr. Russert was a towering figure in American journalism and moderated several debates during the recent presidential primary season. Tom Brokaw, the former anchor of NBC Nightly News, came on the air at 3:39 p.m. and reported that Mr. Russert had collapsed and died early this afternoon while at work. He had just returned from Italy with his family. “Our beloved colleague,” a grave Mr. Brokaw called him, one of the premier journalists of our time. He said this was one of the most important years in his life, with his deep engagement in the network’s political coverage, and that he “worked to the point of exhaustion.” Mr. Brokaw said Mr. Russert was a true child of Buffalo and always stayed in touch with his blue collar roots and “the ethos of that community.”