Ex-Rep. Robert Wexler must refund an unspecified sum of donations he received for the 2010 general election, according to the Federal Election Commission.

In a May 22 letter, the FEC informed Wexler’s campaign committee that it may not retain any contributions designated for the 2010 general election because the Florida Democrat, who resigned from the House in December, is not a candidate.

“Since the candidate is not seeking office and will not participate in the general election, any contribution received for the general election must be returned to the donors,” the letter states. “The use of general election contributions to pay primary debts and obligations is prohibited … as such use could result in individuals making contribution with respect to the primary election in excess of the $2,400 per election limit.”

It is not clear how much Wexler, who resigned to become president of the Center for Middle East Peace, must refund to donors. According to his first-quarter campaign finance report, the campaign retained $521,574 in cash on hand as of March 31.

Wexler’s campaign is required to respond to the FEC by June 24.