DES MOINES, Iowa (AP) — Conservative fundraising group American Crossroads is filling in for Republican U.S. Senate hopeful Joni Ernst while she participates in Iowa National Guard training for two weeks. Group spokesman Paul Lindsay tells The Associated Press they’re spending $415,000 on a 30-second television ad that begins Tuesday.

Crossroads is spending another $3.1 million in Iowa as part of a $20 million blitz in Senate battlegrounds as the GOP tries to take control of the chamber. The ad mentions Democratic candidate and U.S. Rep. Bruce Braley’s critique of Republican Sen. Charles Grassley’s qualifications to be Senate Judiciary Chairman. The ad calls Ernst, a state senator, “a better choice.”

Crossroads is a super PAC that is unaffiliated with Ernst’s campaign and not bound by federal laws limiting contributions. It is required to disclose donors.