Sen. Ron Johnson (R-Wisconsin) is a terrific guy and senator, IMO.
When he was elected, he sold all his liquid assets just so there would be no question about conflicts of interest. Senate rules did not require him to do so. His record while in the Senate has been solidly conservative.
Unfortunately, he represents a very purple state and is in a really tough reelection battle. His opponent is the guy who used to hold the seat, former Sen. Russ Feingold (D), whom he barely defeated in 2010 with 52% of the vote.
Even though I'm not resident in Wisconsin, I plan on donating heavily to his reelection campaign. I hope other people here join me. He needs all the help he can get.