All of the broadcast networks have aggressively pushed onto the Web over the past two years to interest more people in what they do, particularly at a time the audience for their evening newscasts is growing smaller and older.

ABC streams a "World News" unique to the Internet audience in the mid- afternoon. NBC's Brian Williams contributes to both a video and written Web log during the day. However, NBC doesn't make a replay of "Nightly News" available until 10:30 p.m. ET, after it is shown on television throughout the country.

The concern among network affiliates that Web simulcasts would slice into their TV audiences—making their advertising time less valuable—has been a barrier to TV networks doing this.

But CBS News President Sean McManus said the network was able to reach a deal with its affiliates by arguing that the programs will reach a different audience online. Television ratings for the first few days of the NCAA basketball tournament went up this year even though CBS showed the games on the Web at the same time, he said.

"It makes sense if you have access to a television, why would you want to watch it on computer?" he said.

People will have to specifically register online to see the Web simulcast, however, in order to prevent people in later time zones from watching the news before it is broadcast in their area, CBS said.

McManus envisions the online simulcast appealing to people stuck late in the office or commuting with a laptop who might want to be filled in on the day's news.

"I think it could help us potentially grow our audience," he said.

Advertising for the online simulcast will be sold separately, he said.

ABC's afternoon "World News" averages about two million downloads per week, the network said. The Webcast, anchored like the TV version by Charles Gibson, is tailored to the Internet audience, said Jon Banner, "World News" executive producer. For example, in addition to the day's top story, it offers a heavier concentration of technology and pop culture stories, he said.

ABC sees its Webcast less as a way to build its television audience and more as a way to build loyalty among people who seek news online, he said.

"We take the approach—and we believe it's the right approach—that the Internet audience is different from the one watching the broadcast and is looking for different content," Banner said.

CBS is offering its simulcast in the face of trends that show people who watch video on the Web prefer it in shorter bursts. But CBS said Internet users who prefer this approach will still be able to pick and choose news video from the network's Web site.

The network also said it was setting up a new Web log, "Couric & Company," that will include written and video contributions about the news from CBS personnel.