President Donald Trump on Saturday accused Indiana Democratic Sen. Joe Donnelly of trying to “steal” his re-election bid by purchasing Facebook ads for the libertarian candidate on the ticket to siphon votes from his GOP foe.

Several polls have Donnelly in an uphill fight against businessman and political newcomer Mike Braun, the Republican nominee. Inside Elections with Nathan Gonzales lists the race as a Toss-up. Libertarian candidate Lucy Brenton is running far behind the Democratic and Republican candidates.

The president did not present evidence in the accusatory tweet beyond citing an unexplained “rumor.” 

Indiana Democratic Party Chairman John Zody responded to Trump by saying “the ads highlighting how Lucy Brenton is the true conservative in the Indiana Senate race are paid for by the Indiana Democratic Party.”

“They are perfectly legal, factual, and accurately represent Lucy Brenton’s anti-tax record. These ads draw attention to Rep. Braun’s record of voting to raise taxes on Hoosiers dozens of times as a State Representative while writing legislation to give himself tax breaks,” Zody said in a statement.

Trump was in the Hoosier State Friday night to stump against the Democratic senator.

Watch: Highlights From the Final Indiana Senate Debate