Who is Claude Rassmussen from In the Lake of the Woods and what is their importance?

Claude Rassmussen is the owner of lakefront property at the Lake of the Woods, he calls John with the offer for John and Kathy to use the cabin for a few days following John's traumatic political defeat. Claude is a down-to-earth man who tells John soon after Kathy's death that it would help John's cause if he acted as if he was concerned.