But the primary is especially important for those candidates who face only nominal, or no, challengers in the Nov. 4 general election.
Election officials predicted a 15 percent turnout, less than in 2010 when both parties had competitive gubernatorial primaries. This year, former Trek executive Mary Burke faces a nominal challenge from state Rep. Brett Hulsey in a Democratic primary that will determine who gets to take on Gov. Scott Walker, who is unopposed in the Republican primary.
Two of the highest profile races are a four-way Republican primary to help determine who will succeed retiring U.S. Rep. Tom Petri and a three-way contest among Democrats hoping to replace retiring Attorney General J.B. Van Hollen, a Republican.
Five of the eight congressional districts have primary races, as well as five of the 17 state Senate districts and 26 of the 99 Assembly districts. In 10 Assembly districts - five Republican and five Democratic - the winner will face no challenger in the general election.
The Democratic primary for attorney general pits three candidates who largely share the same views on most of the largest law enforcement issues in the state. Two are district attorneys - Ismael Ozanne in Dane County and Susan Happ in Jefferson County. The third, Jon Richards, is a state representative from Milwaukee.
The winner faces Republican Brad Schimel, the Waukesha County district attorney.
The most contentious race in the primary may be the battle between three Republican state lawmakers hoping to succeed Petri, who represents a Republican-leaning district that covers the east-central part of the state, including the cities of Oshkosh, Fond du Lac, Manitowoc and Sheboygan.
Sens. Joe Leibham and Glenn Grothman and Rep. Duey Stroebel agree on the big issues important to conservatives, including a desire for fewer federal regulations, a balanced budget and lower taxes and spending.
With so much agreement, differences have largely come down to bickering over votes on specific bills or one candidate decrying donations made to another by special interest groups. Grothman faulted Leibham for a $5,000 donation from a labor union that shares Leibham's interest in transportation issues. Stroebel attacked Grothman for voting to establish the state's renewable energy standards, which Grothman now says he wants to undo - or at least alter.
In the end, voters' choice may come down to style. The genial Leibham presents himself as someone who can get along with others even in the midst of disagreement, while Grothman bluntly criticizes welfare programs, the federal Education Department, immigrants who cross the border illegally - and members of his own party.
"Nothing bothers me like a big-government Republican," he said during a recent debate in Plymouth.
Stroebel has worked to present himself as an outsider, with only one full term in the Legislature and a wealth of business experience, mostly in real estate. He has spent hundreds of thousands of his own dollars on the race, some of it going to finance ads attacking his opponents and other "career politicians."
A fourth candidate, former technical college instructor Tom Denow, has largely been overshadowed by the better-known and better-funded lawmakers. The winner will advance to take on Democrat Mark Harris, Winnebago County executive.
Polls open statewide Tuesday at 7 a.m. and close at 8 p.m.