The one-hour show, "CNN Election Center," will be hosted by John Roberts and a rotating collection of other CNN personalities. It will air opposite its rivals' prime-time heavyweights, Bill O'Reilly on Fox News Channel and Keith Olbermann on MSNBC.

The show displaces an hour hosted by Rick Sanchez and is a quick response to public interest in the campaign.

The three news networks collectively averaged 8 million viewers for their prime-time coverage of the New Hampshire primary. The same night in 2004 was watched by 3.57 million, according to Nielsen Media Research.

It was a similar increase for Iowa caucus coverage, from 3.4 million in 2004 to 6 million this year.

"There is no question that this political campaign is bewitching viewers," said Jon Klein, CNN U.S. president. "We're having so much fun covering it that we wanted to do more of it on the air."

ABC News also drew more than 8 million viewers to its prime-time debates the Saturday before the New Hampshire primary, well above what it typically does that night with entertainment programming. ABC responded by scheduling a half-hour New Hampshire wrap-up in prime time last Tuesday, the only broadcast network to take that step.

With no incumbents running this year, history suggested ratings would go up, "but it would not have suggested these numbers," Klein said.

CNN has done well with its "Ballot Bowl" weekend specials, giving extended coverage to what the presidential candidates are saying during campaign appearances.

The cable network earned a rare prime-time victory over Fox News Channel on New Hampshire night, by a margin of 3.3 million viewers to 3.1 million. Fox beat CNN in Iowa by about the same margin, Nielsen said.

Roberts will be on the road for his hosting duties, teamed with either Wolf Blitzer, Anderson Cooper, Lou Dobbs, John King or Soledad O'Brien in the studio. CNN had set aside that hour for Campbell Brown, lured from NBC News last year, but Klein said it's uncertain when Brown's show will begin.

When it does, it's likely to have a strong component of political news, he said.