GREENSBORO, N.C. - The judge overseeing the criminal trial of John Edwards will sharply curtail the testimony of a key witness for the defense who could raise doubt about whether the former presidential candidate broke campaign-finance laws.

Edwards' lawyers had intended to call former Federal Election Commission Chairman Scott E. Thomas as their first witness Monday morning, but prosecutors objected.

Judge Catherine C. Eagles sent the jury home early so she could listen as Thomas answered questions to preview his intended testimony.

Thomas said it was his opinion that nearly $1 million secretly provided by two campaign donors and used to hide the Democrat's pregnant mistress while he sought the White House in 2008 did not qualify as campaign contributions under existing federal law.

"These are intensely personal, by their very nature," said Thomas, who served on the FEC from 1986 to 2006 after appointments by Presidents Ronald Reagan, George H.W. Bush, and Bill Clinton. "In my view this is a clear-cut case that the payments were not campaign contributions."

Thomas cited past cases before the FEC to support his position, including a $96,000 payment by the parents of former Republican Sen. John Ensign of Nevada to his mistress that was determined not to violate the law.

Thomas also said FEC law was so complicated that reasonable and knowledgeable people could disagree about whether something qualifies as a political contribution. To win a conviction under the law, prosecutors must show that Edwards knew about the scheme and that he knew he was violating the law.

The jury deciding Edwards' fate will not hear any of that testimony.

Judge Eagles agreed with prosecutors that Thomas' opinions and past FEC rulings are irrelevant to their criminal prosecution of Edwards.

She said that the former commissioner made what amounted to a closing argument for the defense and that campaign-finance statutes were not as confusing as Thomas made out.

"It just doesn't seem that complicated to me," Eagles said. "It doesn't seem to me the jury needs the help."

Eagles said she would allow Thomas to take the stand but barred nearly all of his expected testimony. Unable to call Thomas as their first witness, the defense presented Lora Haggard, the chief financial officer of the John Edwards for President committee and the campaign's top staffer in charge of complying with FEC regulations. She said Edwards was never involved in formulating, filling out, or filing campaign-finance reports that were sent to the FEC. In the sixth count of his indictment, Edwards is accused of causing his campaign to file a false report through deceit.

"We never gave him a report to review," Haggard said. "He had no input."