“There is no more destructive force in Washington than Mitch McConnell—he is the architect of the dysfunction that is hurting Kentuckians,” Kanninen said in a statement. “Amy has served her country for more than 20 years, and she will continue to fight for Kentucky as senator. I’m honored to be a part of that fight.”

Nickolas will stay on with the campaign as a senior adviser overseeing paid media.

The McConnell campaign was quick to highlight the move, tweeting the McGrath campaign “needed to find someone with better expertise in lighting millions on fire.”

The change is the latest sign of problems for McGrath, who has raised huge sums of money in her bid to take out McConnell but has had trouble effectively hitting the longtime GOP lawmaker.

McGrath, who raised $17.4 million in the second quarter, faced a tougher than expected primary against Democratic state Rep. Charles Booker, who was endorsed by Sen. Bernie Sanders (I-Vt.) and Rep. Alexandria Ocasio-Cortez (D-N.Y.). Booker ultimately lost by less than three percentage points, after McGrath outspent him almost 10 to 1 in television ads.

A recent survey from Quinnipiac University had McConnell leading 49 percent to 44 percent, with 5 percent of voters undecided. But another poll from Morning Consult had McConnell beating McGrath 53 percent to 36 percent.