CBS issued its own statement this evening, saying: “CBS News regrets not being able to offer the Democratic presidential debate scheduled for Dec. 10 in Los Angeles. The possibility of picket lines set up by the Writers Guild of America and the unwillingness of many candidates to cross them made it necessary to allow the candidates to make other plans.”

The Writers Guild of America represents both the news and entertainment writers involved in the labor disputes with CBS, but the news writers operate under a separate contract from the scriptwriters. All the networks and Hollywood production studios have been hit by the scriptwriters’ strike, but only CBS News would be affected if the news writers go ahead with a strike. That group voted earlier this month to authorize a strike, but no date has been set for one.

Sherry Goldman, a spokeswoman for the Writers Guild of America East, which represents the news writers, said today that a report posted on several Web sites, which asserted that the news writers had voted to begin a strike on the day of the debate, was untrue. “I don’t know where they got that information,” Ms. Goldman said. She explained that the “board and counsel” of that union would have to meet and vote on setting a strike date and no such meeting has taken place.

“No one in any sense has made a decision about anything,” Ms. Goldman said. The news writers have been working at CBS without a contract for more than two years.

The debate on Dec. 10 was never scheduled to run on the entire CBS network, as individual stations would have been able to choose whether to broadcast it or not. But the 90-minute debate would have taken place from 5 p.m. to 6:30 p.m. Pacific time, putting the Democratic tussle into prime time in the East and Midwest and making it unlikely that many stations in the Eastern or Central time zones would have chosen to carry the debate. It would have been available on CBS’s Web site.