Not really a morning person?

NBC’s Katie Couric is contemplating leaving her perch at the top-rated “Today” show to take over the third-place “CBS Evening News.” ABC executives, meanwhile, have been weighing the best use of veteran anchor Charles Gibson: Should they keep him on “Good Morning America” or tap him to take over “World News Tonight”?

The behind-the-scenes discussions, which have consumed the television news industry in recent weeks, underscore the two often contradictory forces that increasingly shape the broadcast television news divisions.

The contrast between them is as different as, well, day and night.

On one hand are the morning news programs, whose expanding audiences and lengthy running times have made them top revenue generators for the networks. But for all of their value, it’s the evening newscasts -- which earn less money but substantially more esteem -- that remain the flagship shows.

Faced with a limited pool of top stars, network executives are now trying to navigate those crosscurrents as they plug the holes left by Dan Rather’s departure from the “CBS Evening News” and the recent death of ABC anchor Peter Jennings.

“This is a real dilemma in terms of where the networks want to go,” said Charles Bierbauer, a former correspondent for ABC and CNN who is now dean of the University of South Carolina’s College of Mass Communications and Information Studies. “Are they following their heads or their hearts here? Is it about prestige or is it about profits?”

Network news executives didn’t always have to make such a choice. In their early years, the news divisions lost money, a fact the television networks accepted because the newscasts imbued them with a certain amount of stature. But once the networks became absorbed by large corporations, the news divisions were considered profit centers and expected to contribute their share of revenue.

The morning newscasts -- with their longer formats, opportunities for corporate sponsorship and largely female audiences coveted by advertisers -- emerged as the most profitable news shows. Even though “Today,” “Good Morning America” and “The Early Show” don’t attract as many viewers as their evening kin, the overall audience in the morning is steadily expanding, while the evening news viewership continues to shrink.

Together, the morning shows generated a combined sales revenue of more than $1 billion so far this year -- almost three times the amount brought in by the evening newscasts, according to Nielsen Monitor-Plus, which tracks network advertising. “Today” -- which runs an hour longer than its competitors -- has made an estimated $250 million in annual profits in recent years, a major share of NBC’s overall earnings.

The emphasis on the morning segment’s value to the bottom line worries some network news veterans, who fear that financial considerations threaten to supplant journalistic values.

“What’s at stake is the information function of network television,” said Reuven Frank, who served as president of NBC News from 1968 to 1973 and again in the 1980s. “It is not being assigned what I consider its proper priority, therefore it is at risk.”

Different talents are required for the morning and evening anchor jobs, of course. The affability and flexibility needed for the morning -- segue from the war in Iraq to “Desperate Housewives” stars without missing a beat -- is a far cry from the gravitas needed to anchor the evening news. Some wonder whether Couric, who came of age on TV as a “Today” co-host, can make the jump to a harder-edged format; Gibson, who has frequently served as a substitute anchor for the evening newscast, would seemingly make the transition from morning to evening more easily.

So far, there’s no question that the evening newscasts -- largely free of the frothy lifestyle and entertainment segments that fill much of the morning programs -- are still considered the crown jewels of the networks, the platforms that offer unparalleled status. The fact that Couric is considering leaving the top morning show to take the helm of an evening broadcast that lags substantially behind its rivals speaks to the post’s unmatched influence.

“The anchoring job of the evening news is still the most prestigious job in American journalism, certainly in television journalism,” said Robert Zelnick, chairman of Boston University’s journalism department and former ABC News correspondent. “It is the pinnacle.”

But whether Couric makes the switch rests in part on her value as the face of NBC’s morning show -- and the lengths to which the network will go to keep her on its most profitable newscast.

A similar tug-of-war is being played out internally at ABC. With Jennings’ death and the recent departure of Ted Koppel, Gibson is viewed by many as the network dean, a natural choice to assume the anchor chair of “World News Tonight.”

But moving him off of “Good Morning America” could upset the dynamics of the ensemble show, which relies on a lively interplay among Gibson and co-anchors Diane Sawyer and Robin Roberts. The timing could not be worse. Last spring, the ABC program came close to overtaking “Today,” which has dominated the morning news competition for a decade. Although the NBC show has since widened its lead, ABC could have another opportunity to seize first place if Couric leaves “Today.”

Network officials may decide not to name 62-year-old Gibson to the evening news post for other reasons, of course -- including the fact that ABC may want a younger anchor at the helm. But the decision is being closely watched for what it says about balance of power between the morning and evening newscasts, as much as anything else.

“If they keep Charlie in the morning, what they’re saying is, we don’t want to run the risk,” Zelnick said. “If they take Charlie and put him in ‘World News Tonight,’ that’s a statement that the flagship show is still mightily important.”