The request came after revelations that the Bush administration had paid a prominent black media commentator, Armstrong Williams, to promote the new education law that had been strongly supported by President Bush.
Separately, a Democratic member of the Federal Communications Commission called Thursday for his agency to investigate whether Williams broke the law by failing to disclose that the Bush administration paid him $240,000 to plug its education policies.
Williams, who has apologized for a mistake in judgment, said he had broken no law.
In the same contract as the Armstrong arrangement, the Education Department paid the public relations firm Ketchum for a video that promoted the law and appeared as a news story without making clear the reporter was hired as part of the deal.
The agency has also paid for ratings of news reporters, with points given for flattering coverage.
"Given our jurisdiction over the funds involved, we would appreciate your careful review of the contract with Ketchum and the payment made to Mr. Williams," said Sens. Arlen Specter, R-Pa., and Tom Harkin, D-Iowa, in a letter to Education Secretary Rod Paige.
The letter, dated Wednesday, was obtained by The Associated Press on Thursday.
The lawmakers are the chairman and ranking member of the Senate panel that oversees education spending.
They also asked Paige for a list of any grant, contract or arrangement of public money being used "for public relations or anything similar to the purpose of the Ketchum contract" from the 2002, 2003 and 2004 budget years.
Meanwhile, at an FCC meeting Thursday, Commissioner Jonathan Adelstein said the agency had received about a dozen complaints concerning the Williams arrangement.
"I certainly hope the FCC will take action and fully investigate whether any laws have been broken," Adelstein said.
Through the Ketchum contract, the department paid the $240,000 to Williams' company, the Graham Williams Group, which was to produce radio and TV ads that featured Paige.
The deal allowed Paige and other department officials to appear as studio guests with Williams. And Williams, one of the nation's leading black conservative voices, was to use his influence with other black journalists to persuade them to talk about the law, known as No Child Left Behind.
The department has defended its decision as a "permissible use of taxpayer funds under legal government contracting procedures." Williams, though, has apologized, saying that accepting money and then publicly supporting the law was "an obvious conflict of interests."
Williams, responding to the request for an FCC investigation, said that neither he nor any of the stations that carried his syndicated program violated the law because ads that aired during the show specifically stated they were paid for by the Education Department.
"I was not engaged in any public relations in this campaign. It was strictly advertising," Williams said by phone Thursday. "I'm not concerned about this witchhunt because I know that I've done nothing wrong, nothing illegal."
None of the other commissioners responded to Adelstein's statement during the meeting. Afterward, FCC Chairman Michael Powell, a Republican, and David Solomon, who heads the agency's enforcement bureau, declined to comment.
Generally, the FCC reviews letters and complaints before determining if there should be an investigation. Powell said he had not seen the complaints filed against Williams.