"I have read the (plea) agreement, and I accept responsibility," Crutchfield told U.S. Judge J. Daniel Breen.
Defense attorney William Farmer characterized the money that Crutchfield admitted taking as a "gratuity" rather than a bribe.
"They gave him a gratuity _ thanks for all your help _ long after he had already agreed to support this bill," Farmer said outside court.
Crutchfield and former Sen. Kathryn Bowers, D-Memphis, were the last of the Tennessee Waltz lawmakers still facing trial. The others have pleaded guilty or been convicted at trial.
Bowers' attorney, William Massey, said she would plead guilty on Monday.
"She brings this one blemish to the courtroom but a lifetime of good work and a positive history in the community," Massey said. "We hope to convince the judge it's not necessary to punish her severely."
If prison time is ordered, he said, "that's what she'll do. She's strong."
Tennessee Waltz indictments were returned in May 2005, charging the five with taking payoffs from a company called E-Cycle Management, which turned out to be a creation of the FBI.
Farmer said that Crutchfield, who has served in the General Assembly for 31 years, plans to resign "in due time," before the Legislature returns to session in January.
Crutchfield still will be eligible for a $42,000 annual pension because his membership in the state's retirement system predated changes in a law designed to strip benefits from convicted lawmakers.
He faces a maximum of five years in prison and a $250,000 fine, though federal guidelines for a first-time offender would call for a much lighter sentence. Sentencing was set for Nov. 28.
The indictment against Crutchfield accused him of splitting $12,000 in bribes with a so-called "bagman" and former lobbyist, Charles Love. Love pleaded guilty and was to testify against Crutchfield at trial.
Prosecutors say the Tennessee Waltz investigation is ongoing.
Pushing through a crowd of reporters and photographers outside the Memphis courthouse, Crutchfield refused to talk about Tennessee Waltz.
"I'm ready to go home to Chattanooga right now," he said.
Crutchfield was first elected to the state House in 1956 and served 14 terms in the Senate. He was Senate Democratic leader for six years until losing a caucus vote about five months before the Tennessee Waltz investigation became public.
"It is our hope that this does not obscure what was a record of noteworthy public service. Senator Crutchfield represented the people of his district with distinction for a very long time," Democratic caucus chairman Joe Haynes said in a statement.
In all, 11 people have been indicted on Tennessee Waltz charges, including several officials in Memphis and Chattanooga. Nine of those charged, including Crutchfield, now stand convicted.