Freedom Partners Action Fund, a super PAC controlled by the Koch brothers’ political operation, plans to spend $4 million on ads targeting Democrats in the Pennsylvania, Ohio and Nevada Senate races this week.

The spending was debuted at Charles and David Koch’s donor retreat over the weekend. The Koch brothers have refused to spend on behalf of Donald Trump, choosing instead to pour their resources into Senate contests.

With this latest round of ads, Freedom Partners Action Fund will have spent $24 million on Senate races so far this year, Time reports.

The Nevada ad attacks the state’s former Attorney General Catherine Cortez Masto for taking money from taxi companies and driving Uber out of the state. The group goes after former Ohio Gov. Ted Strickland for “making our lives harder” by raising taxes and fees. And in Pennsylvania, it slams Katie McGinty for being “for the favored few.”

Freedom Partners announced last week that it was spending $1 million on a digital and TV buy in Indiana attacking former Sen. Evan Bayh, who is seeking a comeback this year, for his ties to Wall Street.