Sen. Mary Landrieu (D-La.) has persuaded the Democratic Senatorial Campaign Committee to pull a negative TV ad it was preparing to run that accused her likely challenger, Louisiana state Treasurer John Kennedy (R), of breaking his word to Bayou State voters.

The ad was to attack Kennedy — who will be sworn in for a third term as state treasurer on Monday — for running a statewide campaign in 2007 on a message that “the job’s not done,” and then announcing his Senate bid in late November.

The ad was scheduled to run in the New Orleans and Baton Rouge media markets beginning this weekend.

A source close to Landrieu confirmed Friday afternoon that the second-term Senator, who is considered the most vulnerable Senate Democrat up for re-election this year, asked the party committee to pull the ad after screening it Thursday night.

“She’s really trying to run a positive campaign and she just did not want to put a negative spot on the air right now,” the source said. “On many levels we definitely agree with the underlying point that it was trying to make. However, it was a negative campaign spot and not the tone that the Senator is really efforting to keep right now.”

The Landrieu associate added that the campaign is not proposing a unilateral disarmament on negative campaigning for the coming race. He noted that “as the campaign heats up, clearly we’re going to be attacked and we’re going to respond in kind.”

Kennedy, a former Democrat who jumped to the Republican Party last year to run for a third term as treasurer, was widely expected to run against Landrieu even before the October state election in Louisiana.

A Roll Call poll conducted in early December put Landrieu and Kennedy in a dead heat for the seat, with Landrieu’s slight lead over Kennedy falling within the margin of error.

While mostly playing defense in several open-seat and tough challenger races this election cycle, the National Republican Senatorial Committee has been spirited in attacking Landrieu in what might be its lone pickup opportunity of the cycle.

Just this week, the committee was quick to play up a complaint that one Washington, D.C., watchdog group filed against Landrieu claiming that she accepted campaign contributions in exchange for an earmark.

Landrieu’s office has flatly denied those accusations and released documents that contradict the timeline laid out in the complaint filed by Citizens for Responsibility and Ethics in Washington.

“It’s clear the Landrieu campaign is in panic mode due to the daily reports of corruption and pay for play,” said NRSC spokeswoman Rebecca Fisher. “I’m sure they are looking for any distraction they can find right about now.”

DSCC spokesman Matt Miller declined to comment on the pulled ad when reached Friday afternoon.