Landrieu, Cassidy spar in final Senate debate

Washington (CNN) -- Incumbent Sen. Mary Landrieu, a Democrat, and Republican challenger Rep. Bill Cassidy traded sharp allegations of personal misconduct in the final debate before the Louisiana Senate runoff, scheduled for Saturday, Dec. 6.

Days before the debate, Landrieu attacked Cassidy's medical record, alleging the three-term congressman and doctor padded his payroll by manipulating his time sheet at the Louisiana State University clinic where he practices.

Defending his service, Cassidy admitted he filled out the records himself.

'Whenever you go to a clinic, you fill out charts and you sign sheets, and everybody knows where you are,' Cassidy said.

READ: Landrieu looking for game-changer in runoff debate

But Landrieu was persistent with her allegations.

'I think that you owe the taxpayers an explanation for why you took $174,000 -- which is your salary -- plus $20,000, plus we believe - and until we get all the records -- they also paid for his medical malpractice,' she asserted. 'He's the only doctor in the Congress that has this sweetheart deal. The only one.'

But in addition to defending himself, Cassidy was quick to fire back at Landrieu for using taxpayer dollars to fund her private campaign transportation, a violation for which she has apologized and reimbursed taxpayers for.

'When I treat patients in the public hospital system, clearly those patients benefit,' Cassidy said. 'When she takes chartered jets on taxpayer dime to campaign events, who is it that benefits?'

The contenders also predictably disagreed about other hot-button policy issues, particularly the Affordable Care Act.

Defending her vote for the bill in 2010, Landrieu admitted that while she supported President Barack Obama's signature law, 'it should be improved.'

Cassidy, on the other hand, echoed the Republican mantra that the law should be 'repealed and replaced.'

In addition to highlighting that Landrieu has voted with the President '97 percent of the time,' Cassidy also tried to tie Landrieu to Jonathan Gruber, who served as an adviser during the law's drafting and whose controversial comments about the law and its passage have set off a conservative firestorm.

But Landrieu rejected the association.

'I don't read what Jonathan Gruber says, I don't even talk to Jonathan Gruber,' she said. 'I talk to my constituents.'

Keystone pipeline comes to Senate floor

Tensions also flared over the Keystone XL pipeline and energy policy, gun rights, abortion and racial issues in light of the Ferguson, Missouri, shooting tragedy.

Responding to Landrieu's suggestion that the President's unpopularity in Southern states may be attributable to historical racial bias, Cassidy said, 'Just because you disagree with the President, doesn't make you a racist.'

Landrieu finished just ahead of Cassidy in the all-party primary on Nov. 4, but couldn't draw a majority of the vote, sending the race to a runoff that will be decided on Saturday.

The breakdown of Senate seats starting in January 2015 is now 53 held by Republicans, 44 Democrats and two independents, with the Louisiana Senate race the only undecided contest remaining.

Alexandra Jaffe contributed to this report