The cost of state auditor Matt Rosendale and incumbent senator Jon Tester's battle for the Montana Senate seat has topped $60 million, according to the Associated Press.
The Center for Responsive Politics says outside groups, such as PACs and Super PACs, are extremely financially active in the race. The center says that, as of November 5, outside groups have funneled almost $44 million into the 2018 cycle of Montana's Senate race.
The center lists lists the National Republican Senatorial Committee PAC as the top group that's donating against Tester, and says the democratic nonprofit Majority Forward is the top group donating against Rosendale. The center's data shows outside groups have spent significantly less money overall to support candidates.