The Federal Election Commission has directed Republican Linda McMahon to disclose the recipients of more than $567,000 in payments made by the candidate during the start-up of her campaign for the U.S. Senate.

The payments, for services ranging from political consulting to legal advice to computer assistance, were listed simply as in-kind contributions from the candidate herself on an initial campaign finance report McMahon filed last year. That meant the identities of some of the campaign's vendors, including top-flight Republican political strategists and law firms, were not disclosed to the public.

After The Day first reported on the in-kind contributions in December, the McMahon campaign blasted the article as "erroneous," since the campaign had not received a notice from the FEC requesting more detailed disclosures. And a spokesman said he saw no reason to file additional details with the FEC disclosing the identities of the campaign's vendors.

"Why would we amend or re-file something that without question is filed correctly?" McMahon spokesman Ed Patru said on Dec. 11.

But attorneys for the FEC believe more detail is required. In a letter sent to the campaign on Christmas Eve, the commission instructs the campaign to provide the names of the recipients of McMahon's in-kind payments, information that is "essential to the full public disclosure of your federal election campaign finances."

The notice instructs McMahon's campaign to provide the information by Jan. 28 or face "enforcement action."

Campaigns must disclose the identities of vendors paid for goods and services if the in-kind payments total more than $200 over an election cycle, wrote Robin Kelly, a senior campaign finance analyst at the commission. The threshold for disclosure is $500 for expenses related to "travel and subsistence."

Among the in-kind contributions in McMahon's October quarterly filing are substantially larger expenditures, including tens of thousands paid for legal advice and consulting work.

Patru, the campaign spokesman, said in e-mail exchanges last year that many of those expenses were paid for by McMahon herself because they occurred before her formal declaration of her candidacy, and before the campaign committee's accounts were set up. Patru also provided a list of some vendors paid by the campaign, including the law firm Bryan Cave, the prominent Republican consulting firm November Inc., and RAD Computing, but not an itemized list of the disbursements to each vendor.

"The campaign is reviewing the routine correspondence that it recently received from the FEC concerning the campaign’s third-quarter report, and the campaign will respond appropriately to the correspondence well ahead of the Jan. 28 due date," Patru said Tuesday in an e-mail message.