Rep. David Rivera (R-Fla.) did not sufficiently explain some $60,000 in campaign expenditures during his eight years in the Florida state legislature, according to a review of his filings by The Associated Press. 

It's just the latest bad news for Rivera, who already faces a criminal investigation into allegations of secret payments made to a company that he has ties to.

More from the AP:

Serving as his own campaign treasurer, the Miami Republican didn't report any details for more than a third of the roughly $160,000 in expenses for which he reimbursed himself, other than simply calling them campaign expenses, according to the records.

The AP review also shows his total reimbursements far exceeded those claimed by 12 other top Florida state legislators who served with him. Those lawmakers — both Democrats and Republicans — usually gave at least some explanation of how the money had been spent, as required by Florida law. Rivera denies wrongdoing.

Responding to questions about the unexplained payments, Rivera insists he followed state and federal law and never took money that wasn't a legitimate reimbursement. It would be against state law to divert campaign donations to personal use.

"Reimbursements were for campaign-related expenditures such as travel, meals, and supplies. The campaign reports speak for themselves. All information provided was accurate and all expenses properly reported," he said in a statement Thursday through his campaign.

The investigation is proving to be an early headache for House Republicans. 

Earlier this week, House Speaker John Boehner (R-Ohio) declined to address the Rivera investigation that is already ongoing, telling reporters that he is withholding judgment, but that Republican leaders are watching the situation.

"We're waiting to see how this plays out," Boehner said.   

Democrats have jumped on the Rivera story, pointing to GOP promises that the new Republican majority would impose a "zero tolerance" policy with regard to ethics violations. 

During the 2010 midterm cycle, Republicans cited the ethics woes of Reps. Charles Rangel (D-N.Y.) and Maxine Waters (D-Calif.) as evidence that then-Speaker Nancy Pelosi (D-Calif.) didn't follow through on her promise to "drain the swamp."

Rivera won an open seat race this past cycle against Democrat Joe Garcia, and Florida Democrats are already talking to potential candidates ahead of 2012.  

—Jordan Fabian contributed.