On one, polls that are “tightening” are emphasized over those that are not, and the rest of the news media is portrayed as papering over questions about Mr. Obama’s past associations with people who have purportedly anti-American tendencies that he has not answered. (“I feel like we are talking to the Germans after Hitler comes to power, saying, ‘Oh, well, I didn’t know,’ ” Ann Coulter, the conservative commentator, told Mr. Hannity on Thursday.)

On the other, polls that show tightening are largely ignored, and the race is cast as one between an angry and erratic Mr. McCain, whose desperate, misleading campaign has as low as a 4 percent chance of beating a cool, confident and deserving Democratic nominee in Mr. Obama. (“He’s been a good father, a good citizen, he’s paid attention to his country,” Chris Matthews, the MSNBC host, said Wednesday night in addressing those who might be leaning against Mr. Obama based on race. “Give the guy a break and think about voting for him.”)

And, perhaps unsurprisingly, each campaign is often at war against its television antagonist, just as the networks are at war with each other.

It is a political division of news that harks back to the way American journalism was through the first half of the 20th century, when newspapers had more open political affiliations. But it has never been so apparent in such a clear-cut way on television, a result of market forces and partisan sensibilities that are further chipping away at the post-Watergate pre-eminence of a more dispassionate approach.

The more objective approach came as the corporate owners of the networks pushed for higher profits and the newspaper industry consolidated and sought broader audiences. “To sell as many copies as you could to as many people as you could, you became what we considered objective,” said Richard Wald, a professor of media and society at Columbia University School of Journalism and a former senior vice president at ABC News.