Mary Landrieu's Terrible, Horrible, No Good, Very Bad Week

— -- It’s been a tough week for Sen. Mary Landrieu.

If it wasn’t bad enough that the three-term Louisiana Democrat was already considered one of the most vulnerable Democrats in the 2014 midterms -- whose seat could determine control of the Senate -- this week, Landrieu’s re-election bid was rocked by turbulence over a private jet scandal and the announcement that her leading opponent now has more money to spend in the campaign.

The campaign of her GOP challenger, Rep. Bill Cassidy, announced Thursday that he had pulled ahead of Landrieu with $5.6 million cash on hand, according to new FEC filing posted for Landrieu and Cassidy. That’s compared to Landrieu’s $5.5 million.

It’s a small lead of only about $100,000, but a significant one for Cassidy. This is the first time he has managed to outdo Landrieu’s deep fundraising pockets, and his campaign celebrated the achievement.

"We are incredibly excited about the state of our campaign,” Cassidy campaign spokesman John Cummins said in a statement Thursday. “Dr. Cassidy's message of common-sense conservative reform is resonating. That's why he has proven one of the most prolific fundraisers of this cycle and is the only Senate challenger in the country with more cash on hand than the incumbent."

But the Landrieu campaign countered that Cassidy’s cash on hand number is “inflated” by the inclusion of $400,000 that could only be used after Nov. 4 in the event that no one candidate receives more than 50 percent of the vote, in which case the two candidates with the largest number of votes would proceed to a runoff.

"We have always had the funds necessary to run the campaign we planned and will raise all the money we'll need to get out the message that Mary is fighting for Louisianans in the Senate,” Landrieu campaign communications director Fabien Levy said in a statement. “Congressman Cassidy has chosen to inflate his fundraising numbers by including nearly $400,000 in runoff contributions that will be sitting in the bank when Sen. Landrieu wins this election on Nov. 4."

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Cassidy’s cash announcement was just the final straw in Landrieu’s terrible, horrible, no good, very bad week.

Things started to get bumpy on Tuesday when a CNN report alleged that Landrieu had used taxpayer funds to pay for a charter flight to attend a campaign fundraiser. Landrieu spent $3,200 on a round-trip flight from New Orleans to Lake Charles, Louisiana, where she attended a $40-per-person fundraiser with women supporters Nov. 8. The flight should have been paid for by Landrieu’s campaign but was instead reportedly paid for by her Senate office, which is a violation of federal law.

The report came on the heels of a USA Today report a week earlier that said Landrieu was among one of the Senate’s biggest spenders in chartering flights for official Senate business, racking up a $47,000 tab in 2013.

Landrieu campaign communications director Fabien Levy told ABC News it was a mistake that taxpayer dollars were used to pay for the flight to Lake Charles and that the campaign took action “immediately” to correct the error when it was first discovered by her office on July 29.