Very early this morning, after many voters had already gone to sleep, the conventional wisdom of the elite political pundit class that resides on television shifted hard, and possibly irretrievably, against Senator Hillary Clinton’s continued viability as a presidential candidate.

The moment came shortly after midnight Eastern time, captured in a devastatingly declarative statement from Tim Russert of NBC News: “We now know who the Democratic nominee’s going to be, and no one’s going to dispute it,” he said on MSNBC. “Those closest to her will give her a hard-headed analysis, and if they lay it all out, they’ll say: ‘What is the rationale? What do we say to the undeclared super delegates tomorrow? Why do we tell them you’re staying in the race?’ And tonight, there’s no good answer for that.”

It was not exactly Walter Cronkite declaring that the Vietnam War would end in stalemate. But the impact was apparent almost immediately, starting with The Drudge Report, the online news billboard that is the home page to many political reporters in Washington and news producers in New York. It had as its lead story a link to a YouTube clip of Mr. Russert’s comments, accompanied by a photograph of a beaming Mr. Obama with his wife, Michelle, and the headline, “The Nominee.”

The thought echoed throughout the world of instant political analysis, steamrolling the Clinton campaign’s attempts to promote the idea that her victory in Indiana was nonetheless an upset in the face of Mr. Obama’s heavy spending and his campaign’s predictions that he would win there, or that she could still come back if delegates in Florida and Michigan are seated.