Okay, that's what the Hill says in the headline and yes, this might be semantic parsing, but here's what they quote him as saying:

"I fundamentally disagree with Tammy on almost everything. She has a more liberal voting record than almost anybody in Congress," he told The Hill in a recent interview. "Her philosophy has its roots in Marxism, communism, socialism, extreme liberalism — she calls it progressivism — versus mine, which is rooted in free-market conservatism."

I wouldn't disagree with any of that, and I'm not sure Baldwin does either. Here is her campaign's response:

"Unlike Tammy, who has worked across party lines to crack down on China’s cheating, protect Wisconsin manufacturing jobs, and invest in small businesses, Hovde clearly has no interest in bipartisan work to create jobs and move our economic recovery forward," Baldwin spokesman John Kraus said. "Had he not spent the last 24 years in Washington D.C. working as a hedge fund banker, he might know that Wisconsin voters will not buy the increasing desperate and divisive politics he is selling."

Classic non-denial denial. And no, he didn't call her a communist, but said communism is one of the philosphies that help construct her ideology. I'd love to hear her deny that.