Wisconsin voters will head to the polls on Tuesday to cast ballots in the partisan primary races for governor and U.S. Senate, along with a number of other offices.

The election marks the end of a crowded Democratic race for the chance to challenge Gov. Scott Walker in November’s general election. It also concludes an expensive and divisive battle to determine the GOP challenger to incumbent Democratic U.S. Sen. Tammy Baldwin.

Offices on the ballot include governor, lieutenant governor, attorney general, secretary of state, state treasurer, U.S. senator, U.S. representative, odd-numbered state Senate seats and all state Assembly seats.

Some counties will also have races for sheriff, clerk of the circuit court and coroner.

Polls will open at 7 a.m. and close at 8 p.m. Residents can find their polling place and see a sample ballot online at myvote.wi.gov.

Voters can register to vote in-person on Election Day at their polling place, as long as they provide proof of residence. A photo ID is required to cast a ballot.

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"Something most people have, like a Wisconsin driver license or state ID card," said Reid Magney, spokesman for the state Elections Commission. "If you don't have one of those, a passport, a military ID, a veterans ID card ... there's also a number of student ID cards that will work."

Magney also reminded voters they can only vote in one party’s primary.

"Wisconsin's one of the few states that allow people to say, 'I'm going to be a Republican today, I'm going to be a Democrat, I'm going to be a Green, or a Libertarian,'" he said. "You get to decide on Election Day which race you're voting in."

Turnout is generally low in primary elections in years without a presidential race. Magney said the commission expects turnout to be between 15 and 20 percent.

Magney said the commission has taken recent steps to ensure greater election security, amid increased national attention on election hacking and voter fraud.

"We’ve done a lot of training with county clerks and municipal clerks," he said. "If any problems do arise, we can handle them."