U.S. Sen. Mel Martinez said Friday that the Federal Election Commission is auditing his 2004 campaign financial records.

The Orlando Republican said in a statement that he is cooperating with the FEC and blamed apparent accounting errors on the unexpected success his campaign had in raising and spending more than $12 million in a 10-month span.

"As we looked back at the campaign in 2005, we recognized there were problems," Martinez said. "Last summer, I hired the best accountant and lawyer in campaign finance law to go line by line through our filings to correct any discrepancies."

Martinez defeated Democrat Betty Castor, former state education commissioner.