Businessman Eric Hovde (R) jumped into the race to replace retiring Sen. Herb Kohl (D-Wis.) in early March. It was late compared with the rest of the GOP field, but now that he is in, he is making a serious effort in his campaign.

Today, he has put up his second ad on the Wisconsin air, and a source who tracks ad spending said the buy was $450,000. The source also noted that Hovde spent $400,000 on his first ad buy. Between the two ads, Hovde has spent $850,000 on advertising in his first six weeks of campaigning.

“I think by this shift to a sense of entitlement and dependence on government, we’re losing a bit of our soul to be honest,” he says in the ad. “We have to get back to self-responsibility.”

The GOP field seemed set in the fall, but Hovde’s entrance weeks ago has the potential to shake up previous calculations.

State Speaker Jeff Fitzgerald, former Rep. Mark Neumann and former Gov. Tommy Thompson are also in the GOP primary. The winner will face presumptive Democratic nominee Rep. Tammy Baldwin in one of the most heated general-election Senate campaigns in the country.