(CBS News) GREENSBORO, N.C. - John Edwards' daughter was expected to testify Tuesday at the former senator's corruption trial.
Cate Edwards would be the first family member to do so.
The defense began laying out its case Monday, shifting the focus from Edwards' affair to the nuts and bolts of campaign finance law.
But the former senator's lawyers suffered an immediate setback.
The judge ruled that a former election official will be allowed to take the stand, but that most of his testimony would be barred. Edwards' lawyers considered some of that testimony key to his case. He was ready to say there was no crime committed.
Judge Catherine Eagles threw out most of the proposed testimony from former Federal Election Commission Chairman Scott Thomas after prosecutors objected Monday, arguing his opinions and past FEC rulings are irrelevant to the case.
Eagles sent the jury home while Thomas gave a preview of his testimony, saying the use of nearly $1 million to cover up Edwards' affair with Rielle Hunter wasn't illegal.
Thomas told the court that, in his opinion, "This is a clear-cut case that the payments were not campaign contributions," and thus, did not have to be reported as such.
Even before Edwards was indicted last June, Thomas wrote in a letter that the "payments would not be considered to be ... campaign contributions" and that the "payments did not constitute a violation of the law."
But the judge ruled that information would be inadmissible.
Edwards attorney, Abbe Lowe, protested, telling her he thought her decision might constitute a "reversible error" that could be overturned on appeal.
Eagles fired back, saying, "That sounds like you're arguing with me."
Earlier Monday, the jury did hear from Lora Haggard, the chief finance officer for Edwards' 2008 presidential campaign.
From the stand, she said she never thought the money from wealthy donors Bunny Mellon and Fred Baron ever had to be reported to the FEC, even after charges were filed against Edwards.
She said, "They were not contributions to the campaign to urge the public to vote for Mr. Edwards."
It's still unclear whether Edwards himself will testify, but Cate has been by his side daily, and she could take the stand as early as Tuesday.
To see Anna Werner's report, click on the video in the player above.