Voters in both the Democrat and Republican parties will go to the polls Tuesday.
Democrats will pick one of eight candidates dueling it out for the chance to take on Republican Governor Scott Walker in November.
State superintendent Tony Vvers is the only one to have previously been elected in a statewide race, and he currently leads in the polls.
Former State Representative Kelda Roys and state firefighter union leader Mahlon Mitchell are hoping that younger voters provide them a boost.
Other candidates are Matt Flynn, Mike McCabe, Josh Pade, Paul Soglin, and Kathleen Vinehout.
On the Republican side, the race for Senate is between former Marine Kevin Nicholson and State Senator Leah Vukmir.
The winner there will take on Democratic Senator Tammy Baldwin.
The primary is partisan, meaning you can only vote for one party.
You must bring a photo ID and show up to your assigned polling place.
Polls are open from 7 a.m. to 8 p.m.
