Check out the pics on Yahoo's Tom Delay story

DeLay is under indictment in Texas as part of an investigation into the allegedly illegal use of funds for state legislative races.

Separately, the Texan's ties with lobbyist Jack Abramoff caused him to formally surrender his post as majority leader in January, within days after the lobbyist entered into a plea bargain as part of a federal congressional corruption probe.

More recently, former DeLay aide Tony Rudy said he had conspired with Abramoff and others to corrupt public officials, and he promised to help the broad federal investigation of bribery and lobbying fraud that already has resulted in three convictions.

Neither Rudy, Abramoff nor anyone else connected with the investigation has publicly accused DeLay of breaking the law, but Rudy confessed that he had taken actions while working in the majority leader's office that were illegal.

DeLay has consistently denied all wrongdoing, and he capped a triumph in a contested GOP primary earlier this year with a vow to win re-election.

In an interview Monday with The Galveston County Daily News in Texas, DeLay said his change of mind was based partly on a poll taken after the March Republican primary that showed him only narrowly ahead of Democrat Nick Lampson.

"Even though I thought I could win, it was a little too risky," the paper quoted him as saying.

In a separate interview with Time Magazine, DeLay says he plans to make his Virginia condominium his primary residence, a step that will disqualify him from the ballot in Texas and permit GOP officials there to field a replacement candidate. "I can do more on the outside of the House than I can on the inside right now. I want to continue to fight for the conservative cause. I want to continue to work for a Republican majority," DeLay told the magazine for its online edition.

It was not clear Monday night whether Texas Gov. Rick Perry would call a special election to fill out the unexpired portion of DeLay's term, or whether the seat would remain vacant until it is filled in November.

DeLay was the driving force behind President Clinton's impeachment in 1999, weeks after Republicans lost seats at the polls in a campaign in which they tried to make an issue of Clinton's personal behavior.