Wisconsin Republicans are choosing among three candidates to pick a challenger for Democratic Sen. Russ Feingold.
Businessman Ron Johnson is widely viewed as the prohibitive GOP favorite in Tuesday's primary.
Johnson, who made a fortune with his Oshkosh plastics company, has poured $4.5 million into the race. That made him a prohibitive favorite against Dave Westlake, a small-business man and West Point graduate who ran a shoestring campaign on a budget of less than $100,000 and ran only one radio ad.
Both Johnson and Westlake are political neophytes. It was Johnson's wealth, and his willingness to spend it against Sen. Feingold, that helped him win the GOP's endorsement just six days after he entered the race.
A third Republican candidate, Milwaukee plumber Stephen Finn, has been largely invisible.
