Two liberal groups paid for the 30-second ads, which address alleged links between DeLay and a widespread congressional corruption probe of disgraced lobbyist Jack Abramoff.

The ads were to start Wednesday and run for one week. But the DeLay campaign sent letters to the stations threatening legal action, saying the spots are deliberately misleading.

"The ad is reckless, malicious, and false, casting Mr. DeLay in a false light by accusing him of unsubstantiated criminal conduct," DeLay campaign lawyer Don McGahn wrote the stations. "We demand that you refuse or otherwise cease airing the advertisement."

KHOU-TV, a CBS affiliate, announced on its 5 p.m. broadcast that it was skipping the ads because "not all the claims in the ad could be clearly substantiated from the source material."

ABC affiliate KTRK-TV and Fox affiliate KRIV-TV also declined to air the spot, which was paid for by Campaign for America's Future and Public Campaign Action Fund.

Toby Chaudhuri _ a spokesman for Campaign for America's Future, one of the groups that paid for the ad _ said in a statement that "threatening to sue the media and desperately throwing dust in the eyes of his constituents rather than answering the charges against him won't help Rep. DeLay's defense."

The ad lists money and travel that DeLay allegedly received from Abramoff, who pleaded guilty this month to corruption charges in connection with congressional wining and dining.

DeLay stepped down as House majority leader earlier this month. He had been forced to temporarily relinquish the Republican leadership post after he was indicted in September.