Feingold is a democrat and an incumbent since 1992. In the normal circumstances, Feingold would be a sure win. He's been in office a long time and hasn't been involved in any wide spread scandal. However, with the disdain for the incumbents, particularly in the aftermath of the Health Care Bill passage, he's going to have to work hard to keep his position.
Feingold is Harvard educated, and got his degree in 1979. He's been in politics since 1982 when he was elected to the state Senate in Wisconsin. He serves on the HSenate committees for the Judiciary, Budget, Foreign Relations, and Budget & Intelligence, and chairs the subcommittees on the Constitution and African Affairs. Another claim to fame was that he was the only person to vote against the PATRIOT Act in the wake of the 9/11 terrorist attacks.
Rasmussen reports put Johnson ahead of Feingold by 7 points. However, the race could be packed full of suspense as some polls only have them a couple of points apart.
Ron Johnson has given speeches for the Tea Party on occasion. He's backed by the Dairy Business Association and Senator Jim DeMint. He's is against additional government spending, the "cap and trade" bill, the health care bill, and the registration of firearms. He wants to reduce taxes, provide solutions for healthcare in the capital markets, and penalizing companies that hire illegal aliens.
The Feingold-Johnson race is indicative of the general push that many incumbents are feeling. With Johnson's relationship with the Tea Party, this is just another illustration of how hard things have become.