The flamboyant ex-House Republican leader’s strong-arm politics earned him the nickname "The Hammer" for his ability to push through President George W. Bush's legislative agenda in Congress.
Congressman DeLay has announced that he will give up his US Congress seat and end his bid for reelection in November's mid-term congressional elections.
"It's time for me to go and do something else," he told Fox News Channel on Tuesday.
The former pest control expert had become one of the most polarizing figures in US politics in recent years. But he has also been eminently successful in instilling lock-step party discipline among Republicans and delivering votes on legislation critical to his party.
He was also valued for formidable skills raising funds from legions of well-heeled Washington partisans.
He also counted among his close associates disgrace former super-lobbyist Jack Abramoff, who is now cooperating with prosecutors in several Capitol Hill corruption cases including against DeLay himself.
Pivotal figure
Mr Bush told reporters that after being informed of Mr DeLay's decision, he wished him well and said he was sure that the party would prove resilient in the face of the setback.
"My reaction was, it had to be a very difficult decision for someone who loved representing his district in the state of Texas. I wished him all the very best and I know he's looking to the future," the president said.
"My own judgement is that our party will continue to succeed because we're the party of ideas," said Mr Bush.
Congressman DeLay, 58, stepped down from his leadership post after a Texas grand jury indicted him for alleged campaign finance violations and his legal troubles mounted.
A pivotal figure in the Republican Party for a dozen years, he came into office with the when Republicans seized control of Congress in the historic mid-term elections of 1994.
But his legal and ethical problems had begun to drag down his party, leaving it vulnerable to Democrats' charges that Republicans are plagued by a "culture of corruption."
Mr DeLay said that despite his recent legal woes he believed he had a good chance of holding onto his seat representing a Texas district, but did not want the criminal case against him to become a dominant election-year issue nationally.
He repeated his assertions of his innocence, telling Fox News that he has served in Congress "honorably and ethically."