A Democrat-leaning group filed a complaint accusing U.S. Sen. David Vitter of violating a state campaign finance law.

The American Democracy Legal Fund accused Republican Vitter and his Senate campaign of impropriety in contributing $100,000 to a group supporting his 2015 governor’s race bid.

The complaint was filed Friday with the Louisiana Board of Ethics, which functions as the Supervisory Committee on Campaign Finance Disclosure.

The group publicly released the complaint and request for an investigation on Monday.

Luke Bolar, Vitter’s media spokesman, called the complaint a “baseless attack.”

American Democracy cites a state law that bans funds subject to the federal campaign finance laws to be transferred, loaned or contributed by a candidate, his agency or his federal campaign to a committee that supports the candidate for state office.

“Sen. Vitter violated this provision” when his Senate campaign contributed $100,000 to The Fund for Louisiana’s Future — established to support Vitter’s run for governor, wrote Brad Woodhouse, treasurer for American Democracy.

“Louisiana law barred Senator Vitter from transferring these funds to any Louisiana political committee that supports his gubernatorial candidacy. Yet that is exactly what he did,” Woodhouse wrote.

In recent days, American Democracy has filed complaints against campaign practices of Republicans running for U.S. Senate in North Carolina and New Hampshire. Woodhouse is a former spokesman for the Democratic Party and runs an opposition research group.

Washington lawyer Charles Spies formed The Fund for Louisiana’s Future as an independent political action committee for the purpose of supporting Vitter in either Senate or governor’s bids. Spies has said the PAC operates independent of Vitter even though Vitter fundraisers also are paid by the PAC. The Fund for Louisiana’s Future successfully challenged Louisiana’s campaign finance law limiting contributions.

State ethics administrator Kathleen Allen said she could not confirm whether the Vitter complaint had been filed. She said normal procedure would be for complaints to be submitted to the Ethics Board to determine whether they should be referred to investigation. Any discussion would be in a closed-door session, and the public would not know whether an investigation had been ordered.

The board’s next meetings are Thursday and Friday. Its agenda already has been set.

Bolar said the attack comes “from a leftist group headed by a former senior campaign adviser to (President) Obama.”

“Sen. Vitter has and will follow every aspect of campaign finance law,” Bolar said.

Follow Marsha Shuler on Twitter, @MarshaShulerCNB. For more coverage of the State Capitol, follow Louisiana Politics at http://blogs.theadvocate.com/politicsblog.