Washington ( CNN ) -- Louisiana Sen. Mary Landrieu 's campaign paid for more than 12 years of wrongfully taxpayer-funded travel , her office announced on Friday . Landrieu 's campaign reimbursed the federal government $ 33,727 for chartered flights that were wrongly charged to her Senate office . The payment comes a month after the Louisiana Democrat ordered her attorney to audit her office 's travel spending to root out incorrectly-billed campaign travel . Landrieu said the `` mistakes , '' which go back to 2002 , stemmed from `` sloppy book keeping . '' `` I take full responsibility . They should have never happened , and I apologize for this , '' Landrieu said in the Friday statement . CNN first reported in August that Landrieu used government dollars to pay for a chartered flight that took her to a campaign fundraiser last November . Landrieu 's campaign spokesmen said then that the charter company mistakenly billed Landrieu 's Senate office instead of her campaign and that mistake had already been rectified . The next day , Landrieu 's office announced she would refund the Senate for a separate $ 5,700 charter flight after CNN questioned the expense . It was shortly after that report that Landrieu ordered a full review of her travel expenses . Landrieu said her office now has a new system successfully used by other Senate offices to prevent future mistakes . The reimbursed funds accounted for about 11 % of her Senate office 's travel costs over the last 12 years . Marc Elias , Landrieu 's attorney who conducted the review , also wrote in a letter to the Senate Ethics Committee that future taxpayer-funded charter flights would be `` cleared in advance by counsel . '' Rep. Bill Cassidy , a Republican challenging Landrieu for her Senate seat , slammed Landrieu for only disclosing her travel records since 2002 , when the Federal Elections Commission changed the rules on payment for campaign-related travel . `` No matter how Sen. Landrieu spins it , she billed taxpayers for dozens of private jet flights since the turn of the century , '' he said . Cassidy called on Landrieu to release her nearly 18 years of travel records as a senator . `` Prior to that ( rule change ) , it was also illegal to bill taxpayers for private flights . Given Senator Landrieu 's own admission of faulty oversight , how do taxpayers know that problems did not exist prior to 2002 ? '' Cassidy said in the statement . Landrieu 's flight troubles first came in late July when USA Today listed Landrieu as one of the Senate 's most frequent flyers after she billed the federal government more than $ 47,000 in chartered flights in 2013 alone .
Louisiana Sen. Landrieu blames `` mistakes '' on `` sloppy book keeping '' She had ordered audit to root out incorrectly-billed campaign travel . `` I take full responsibility . They should have never happened , '' she says . GOP opponent slams Landrieu for only disclosing travel records since 2002 .