Two Baton Rouge television stations Thursday pulled an outside group’s negative campaign ad against U.S. Sen. David Vitter after receiving a letter from the Vitter campaign challenging one of the ad’s claims.

A spokeswoman for the group said they would make a slight change to the ad and have it on the air again on Friday.

The claim dealt with a Vitter staffer in Washington, who, according to his girlfriend, stabbed her at her apartment in 2008. The staffer resigned two years later, news accounts at the time reported.

“The documentation provided by the Vitter campaign made us concerned about one of the claims in the ad,” said Lee Meredith, the general manager of WAFB Channel 9. “We’ve asked that the group substantiate the claim or alter the ad.”

“We felt it was somewhat misleading,” said Rocky Daboval, the general manager for WBRZ-TV. “It’s our responsibility to make certain that all the content of third-party ads is documented.”

The Vitter campaign said three other stations pulled the ad Thursday — stations in Lafayette, Alexandria and Monroe — but The Advocate was not able to substantiate that.

The commercial was produced by a political action committee that calls itself the Louisiana Water Coalition.

The 30-second spot shows a news article and photographs related to Vitter’s 2007 admission that he committed a “very serious sin” in connection with the so-called Washington, D.C., madam. It also airs a news article and clip of another prostitute’s allegation in 2007 that he was her client, as well.

The ad also includes a video clip related to Vitter staffer Brent Furer, who resigned after ABC News reported that his girlfriend accused him of stabbing her two years earlier. The Vitter campaign said Thursday Furer was actually fired.

Meredith said the Vitter campaign provided evidence showing that Furer had not pleaded guilty to that offense.

A 2010 Associated Press article reported that Furer pled guilty to a lesser misdemeanor charge.

Vitter campaign spokesman Luke Bolar did not respond to a request of The Advocate for a copy of the letter.

It was sent by the New Orleans law firm of Sher Garner Cahill Richter Klein & Hilbert.

A spokeswoman for the anti-Vitter group downplayed Thursday’s events.

“There are a few minor technicalities that we intend on correcting,” said Laurie Tate, who the water coalition has identified as its managing member. “They’re trying to divert attention from what we’re bringing to voters.”

Tate, who is a public defender in East Baton Rouge Parish, said the group has made a “substantial and statewide” buy with the ad but declined to provide specifics.

Tate also declined to identify the group’s donors. She said the group would make that information public when it has to file a campaign finance report on Sept. 24.

The group’s website, betterthanvitter.com, directs people to the campaigns of Vitter’s three major opponents: Lt. Gov. Jay Dardenne, Public Service Commissioner Scott Angelle, both Republicans, and state Rep. John Bel Edwards, the only Democrat in the race.

The Vitter campaign says trial attorneys are behind the ad but has not provided any evidence of that.

Meanwhile, the Sexton law firm is no longer representing the Louisiana Water Coalition PAC.

Gray Sexton said on Thursday that his firm’s role was to make sure that the water coalition PAC was complying with state campaign finance laws but resigned the work to avoid an appearance of a conflict because the firm had performed a similar role for Vitter and Dardenne.

Sexton said his firm stepped aside from the Louisiana Water Coalition PAC after receiving a warning letter from Vitter’s gubernatorial campaign.

Sexton said he and Alesia Ardoin, who was identified in the water coalition’s news release as one of its attorneys, played no role in the PAC’s political strategy. He declined to identify who hired the firm.

The Vitter campaign told a different story, with campaign spokesman Luke Bolar emailing reporters to say that Ardoin resigned “after very serious violations.”

Sexton said Ardoin and the firm did nothing wrong.

Sexton worked for years as the attorney for the state ethics board, which oversees campaign finance law, before starting his own firm.

Follow Tyler Bridges on Twitter @TegBridges. For more coverage of the state capitol, follow Louisiana Politics at http://blogs.theadvocate.com/politicsblog/.