One conservative group plans to spend $9.4 million on ads for the open Senate race in Michigan.

The race is already expected to be one of the nation’s most competitive.

One Nation plans to spend a total of $88 million on a “Stop the Insanity” campaign of radio, mail, TV and digital ads in contested races such as those in Ohio, Wisconsin, Montana and Pennsylvania.

Ads are expected to begin after the August primary, focusing on immigration and inflation.

They say it’s the latest big investment in an open state that observers believe will help decide the U.S. Senate majority in the fall.