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Republican Louisiana Senate hopeful Rep. Bill Cassidy is calling on Sen. Mary Landrieu to apologize and return all taxpayer money she has spent on charter flights after a CNN report revealed the Democratic incumbent violated federal law by using taxpayer dollars to charter a private flight to a campaign event.

"Senator Landrieu's disregard and abuse of taxpayer money is unacceptable and, reportedly, illegal," Rep. Cassidy said in a statement. "She should return all the taxpayer money she has spent on charter flights, open up her travel logs for further review to ensure there are not more violations, and apologize to American taxpayers immediately."

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Landrieu spent $3,200 on a round-trip flight from New Orleans to Lake Charles, La., where she attended a $40-per-person fundraiser with women supporters Nov. 8, the same day President Obama was in Landrieu's hometown of New Orleans for another event, which she did not attend.

The flight should have been paid for by Landrieu's campaign but was instead paid for by her Senate office. Landrieu campaign communications director Fabien Levy told ABC News it was a mistake that taxpayer dollars were used to pay for the flight and that the campaign has since corrected the error.

"We take our finances very seriously and are glad we caught the vendor's mistake and were able to rectify the matter as soon as possible," Levy said in a statement.

The campaign discovered the improperly billed flight July 29, at which point Levy said the campaign "immediately contacted the vendor," which Landrieu uses for both official Senate business and campaign flights, to correct the mistake. The Landrieu campaign cut a check Aug. 4 for the corrected invoice from the charter company, and the Senate funds were reimbursed.

Though the Landrieu campaign has corrected the error, which it blamed on the charter company, Cassidy says the senator needs to take direct responsibility.

"Louisiana taxpayers entrusted Senator Landrieu with public dollars," Cassidy said in a statement. "She has a responsibility to use those dollars legally and to uphold the public trust. … This is her budget and in the words of Harry Truman: 'the buck stops here.'"

The Landrieu campaign counters that it's Cassidy who needs to be more transparent with voters.

"If Congressman Cassidy was really concerned about this matter, he'd at least agree to one of the four debates Senator Landrieu has agreed to so they can discuss this in person," Levy said in a statement to ABC News. "I'm sure voters would also like to hear about the numerous issues Congressman Cassidy has refused to give his opinion on, like the cost of education, taxes and whether Louisiana businesses have the resources they need to stay opened."

CNN's report Tuesday came less than two weeks after USA Today reported that Landrieu was one of the Senate's biggest spenders when it comes to chartering flights for official Senate business, having spent $47,000 for such flights in 2013.

Col. Rob Maness, another Republican candidate in the race who has been endorsed by Sarah Palin, has also called on Landrieu to reimburse taxpayers for the cost of all taxpayer funded charter flights and pledged never to violate federal laws if he is elected to the Senate.

"In recent weeks, a disturbing pattern-of-behavior has been exposed revealing Sen. Mary Landrieu's constant abuse of taxpayer dollars," Maness said in a statement. "I want every Louisianan to know with 100% certainty that I will not act with such carelessness and arrogance."