With the trial of a key finance official on Senator Clinton’s 2000 campaign set to open tomorrow, a secretly recorded audiotape at the core of the case could prove embarrassing to politicians, political operatives, and wealthy donors to the Democratic Party.

David Rosen, 40, faces three felony counts of causing the filing of false campaign finance reports in connection with a celebrity-studded fund-raiser and concert held in August 2000 at a radio executive’s estate in the Brentwood hills above Los Angeles.

Prosecutors have asserted that the true cost of the gala was more than $1 million but that Mr. Rosen reported costs of just $400,000 as part of a scheme to increase the funds Mrs. Clinton had to spend on her Senate bid.

Mr. Rosen, now a Chicago-based political consultant, has pleaded not guilty to the charges.

As part of the investigation into the alleged under-reporting, the FBI asked a New Orleans political consultant and friend of Mr. Rosen, Raymond Reggie, to wear a wire and surreptitiously record the former Clinton aide.

In September 2002, Reggie invited Mr. Rosen to dinner at a Chicago steakhouse, Morton’s. There, the two had a freewheeling conversation about the August 2000 fund-raiser, top Democratic Party figures, and the sex-and-drug laced lifestyles of rich donors.

The New York Sun reported last month on an FBI affidavit that detailed Reggie’s role as an informant, as well as Mr. Rosen’s alleged statements that costs for the Los Angeles fund-raiser probably exceeded what was reported to federal officials.

On Saturday, the New Orleans Times-Picayune reported that it obtained a more detailed, but still incomplete, transcript of the conversation. The newspaper said Mr. Rosen expressed doubts about his decision to allow the Clintons to orchestrate the defense of a civil suit that sprung out of the same August 2000 fund-raiser.

“The former White House wanted to hire, or argue the case in a certain way,” the newspaper quoted Mr. Rosen as saying in the transcript. “And I did it for them. Like, I bit the bullet and went in as a guinea pig, and argued their argument for me. Instead of frettin’ and runnin’ and coverin’ my a-, I was a good soldier. … So far it’s worked out, but I coulda done it a lot different.”

The civil suit, brought by a major donor to the August 2000 fund-raiser, Peter Paul, in conjunction with a conservative legal watchdog group, Judicial Watch, named both Clintons, Mr. Rosen, as well as another promoter of the event, Aaron Tonken, and a major Democratic donor, James Levin, as defendants.

In an interview, an attorney for the Clintons, David Kendall, said he was confused by Mr. Rosen’s statement. He said lawyers for the various defendants have made no effort to hide their coordination and have at times filed joint briefs.

“It’s no secret that counsel for Mr. Rosen, the Clinton for Senate Committee, and the Clintons have been cooperating in the defense of a meritless civil suit brought by Peter Paul,” Mr. Kendall said.

Paul, a four-time convicted felon, is pressing forward with his lawsuit, which alleges that the Clintons and their allies swindled him out of $2 million by reneging on a deal under which President Clinton was supposed to work for him after leaving office.

Much of the FBI-recorded steakhouse conversation was devoted to salacious gossip about Clinton loyalists, the Times-Picayune reported. Reached in Los Angeles, Mr. Rosen’s lawyer, Paul Sandler, declined to comment on the exchange.

Among the recorded gripes on the tape was Mr. Rosen’s complaint that although he worked closely with Vice President Gore, Mr. Gore later mistook him for a valet parking attendant, according to the Times-Picayune.

Reggie, who is Senator Kennedy’s brother-in-law, made the tape to win leniency from prosecutors, who were preparing to charge him with bank fraud. Last month, he pleaded guilty to two felony counts. Reggie and his attorney, Michael Ellis, did not return calls yesterday seeking comment for this article.

Reggie, 43, is expected to be a key prosecution witness at Mr. Rosen’s trial. Others identified as possible witnesses include the chief strategist on Mrs. Clinton’s 2000 campaign, Harold Ickes. Mr. Ickes served as deputy chief of staff under Mr. Clinton and now runs a liberal political action group in Washington, America Coming Together. He could not be reached for comment yesterday.

Also on the list of possible witnesses is Mr. Levin. A prolific Democratic fund-raiser and overnight guest at the Clinton White House, he sat on the national finance committees for Mrs. Clinton and Mr. Gore in 2000. After the Chicago Sun-Times disclosed that Mr. Levin once owned a Chicago strip club, Republicans sought to tarnish both Democrats for associating with the windy city businessman.