A group affiliated with Republican Senate Majority Leader Mitch McConnell has reserved $6 million worth of TV airtime in Nevada ahead of the November elections.
The Senate Leadership Fund announced the reservation on Tuesday. Republicans are supporting Rep. Joe Heck in a highly competitive Nevada Senate race to replace Sen. Harry Reid.
A Heck victory could flip the seat from Democratic to Republican hands and help the GOP retain its majority.
Outside groups are already active in the race. A conservative PAC affiliated with the Koch brothers is launching $1.2 million in ads Wednesday attacking Heck's Democratic rival, Catherine Cortez Masto, over her legal challenge of ride-hailing service Uber.
A group linked to Karl Rove is running a $2.3 million ad campaign promoting Heck's military career and work with veterans.