The Senate ad wars in Big Sky Country are raging, with both Democrats and Republicans funneling millions to blanket the airwaves in Montana, a state critical to achieving a majority in the upper chamber. 

Outside groups have already made early ad reservations in Montana, where Sen. Jon Tester (D-MT) is facing what could be his most difficult reelection campaign yet, in a state former President Donald Trump easily won twice. So far, Montana has seen $89.4 million in ad spending from groups on both sides of the aisle, the most of any state, according to a report from AdImpact. Nevada takes second place in ad spending but only saw half as much with $35 million.