A Maine ethics panel found that House Speaker Sara Gideon violated campaign finance laws when she used a corporate-funded PAC to reimburse her political donations, a decision that could play a major role in determining the Senate majority in 2020.

The five-member ethics commission found that Gideon engaged in a "straw donor" scheme after she used the Gideon Leadership PAC to pay for her personal political donations. As the ethics committee deliberated, Republican campaign officials toured Maine with a mobile billboard highlighting the campaign violations committed by Gideon, widely seen as the frontrunner to challenge incumbent Republican senator Susan Collins.

"Good luck defending your scheme to launder your PAC's corporate money into federal elections," the billboard says.

"Gideon's reliance on questionable donors, illegal contributions, or support from dark money special interest groups is a reminder that she will do whatever it takes – legal or illegal – to try to give Maine’s voice away to the liberals in Washington," National Republican Senatorial Committee spokesman Nathan Brand said in a press release.

"Today's Maine Ethics Commission ruling that Sara Gideon broke the law is just another example of her illegal and shady activities," Brand later added.

The complaint stems from a Washington Free Beacon report showing that the corporate-funded committee repeatedly reimbursed Gideon for her personal campaign contributions during the 2016 election cycle. Gideon was listed as the PAC's "decision-maker" for "spending decisions." Gideon appeared to have been reimbursed for her political contributions on four occasions. She dissolved the PAC in June as she prepared to challenge Collins.

A Gideon spokesperson acknowledged the reimbursements in August but said they were the result of "incorrect guidance" from an adviser.

After the Free Beacon‘s report, former Maine state senator Edward Youngblood (R.) filed an ethics complaint against Gideon. The complaint seeks to formally reprimand her for breaking election law.

"She may very well have been misled and probably was," Youngblood told the Bangor Daily News. "But the fact remains that she broke the law and there ought to be a public record that shows that she did."

Federal law prohibits individuals from making contributions in the name of another entity or individual.

Gideon has been a proponent for campaign finance reform and has spoken out against corporate political influence. The NRSC plans to make Gideon's fundraising scandal a centerpiece of the campaign. It has launched a four-figure digital campaign with a website and Facebook and Twitter advertisements.

The website, GuiltyGideon.com, lays out much of the media coverage surrounding the alleged campaign finance violations against the Maine speaker of the house. It also blasts Gideon for attending a fundraiser held by a millionaire Democratic donor who compared the 2019 government shutdown to the 9/11 terrorist attacks.

Gideon is running to unseat Collins, a top 2020 incumbent target, and has already won the backing of national Democrats. Gideon raised more than $1 million in the week after her campaign announcement, according to Politico.

*This piece has been updated to reflect the findings of the Maine Ethics Commission and to include comment from the NRSC.