MADISON, Wisc. — Wisconsin has all the hallmarks of a Bernie Sanders-friendly state: large numbers of college-age voters, a progressive electorate and one of the whiter populations in the country.

But when the state goes to the polls Tuesday, it will feature another element that’s proved just as vital to the Vermont senator’s success – an open primary format where voters don’t need to be Democrats to participate.


It’s one of the main reasons why Sanders is thought to have the edge over Hillary Clinton here. While he’s lost the majority of Democratic primaries that have taken place this year, the three primary wins he’s posted -- New Hampshire, Michigan, and Vermont – have all come in states with open contests where non-Democrats can vote. Aside from caucuses – where Sanders tends to crush Clinton – an open primary usually offers Sanders his best shot at victory.

“He wins independents who say they’re going to vote in a Democratic primary, and it doesn’t matter what their ideology is — whether they’re moderate or liberal, he wins them,” explained Patrick Murray, director of the Monmouth University Polling Institute. “Diehard Democrats who show up regularly in the Democratic primary are going to Hillary Clinton regardless of whether they’re liberal or moderate, so it has a lot to do with how attached voters are to their party identifications."

Sanders will need to take full advantage of Tuesday’s open primary because there aren’t many of them left. There are just 18 states remaining in his nomination contest against Hillary Clinton and just two – Indiana and Montana – are classified as open primaries with no restrictions on who can vote in the Democratic contest.

For the underdog fighting to chip into Clinton’s lead, that means the pressure is on in 86-delegate Wisconsin — and that he has to soon figure out how to win big in states with closed primaries, which carry a hefty portion of the delegates from here on out.

After Wisconsin, Sanders can expect to perform well in the two remaining caucuses in Wyoming and North Dakota. But some of the most delegate-rich states remaining host closed primaries – including New York, Pennsylvania, Maryland and New Jersey – that have worked in Clinton’s favor. California, the biggest delegate prize of all, is semi-closed — meaning it’s open to registered Democrats and those who decline to state a party, but no one else.

The Sanders campaign has worked to educate voters in individual states about the applicable voting laws, including in states like Connecticut where residents can change their party registration until the day before the April 26 primary. But with other states maintaining strict laws that bar registration switches in the weeks leading up to a primary, Clinton is at an advantage given that both campaigns only recently started shifted focus to the April, May, and June states.

“Part of it is [that] some voters will be caught off guard, not realizing that they can’t vote, once we get to some states that are not used to being in the mix in a competitive primary,” predicted Murray.

The Sanders camp, which has long maintained that it intends to compete at least until July’s Democratic convention, insists its poor performance in closed primaries so far will become a thing of the past given the candidate’s winning streak coming out of March — not to mention his soon-to-come investment of time and money for television ads in places like New York, Pennsylvania, and Connecticut, noted the senator’s chief strategist, Tad Devine.

“We’ll see how we do on Tuesday [in Wisconsin]. If we can find a way to win there on Tuesday, it’s a big deal. It’s a battleground state, it’s a statewide primary. In terms of how it looks in the future, a lot of it depends on momentum: we’ve won six of the last seven contests. If we win Wisconsin and then Wyoming, we go onto New York,” said Devine, pivoting to the general election case that Sanders has been making repeatedly on the campaign trail. “Support for him is growing, and I concede we do better with primaries or contests with independents. [But] that’s why we do better in the general election [polling]."

Sanders has already started competing hard in New York, and his campaign is expecting to follow a similar playbook in other Northeastern states, Devine said. His aides often repeat their belief that Sanders does better in states where he can camp out and advertise heavily — and the presence of two nearly empty weeks before New York’s April 19 primary make it easier for him to vigorously campaign there in person and on television. While the state’s expensive media markets make television spending a greater drain on resources, the torrid pace of his small-donor fundraising means he won’t lack for cash.

But New York loses its saliency if Sanders can’t carry Wisconsin, which is essential if Sanders hopes to keep cutting into Clinton’s lead of over 250 pledged delegates. Recognizing he needs a hefty chunk of Wisconsin’s delegates to keep his narrow hopes alive, Sanders has been making a hard press here, headlining eight events in the state between Saturday and Monday alone — many in large college towns like Madison, the linchpin for his chances on Tuesday.

“There is just a plethora of real progressive activism in that town, and that county and that city play an out-sized role in the primary,” explained Dan Kanninen, Wisconsin state director for Barack Obama in 2008, referring to Madison. “With a big university, with same-day registration, you can expand the electorate."

And Sanders — who often predicts victories around the country contingent on high voter turnout — has also been working to turn his White House campaign into a statewide referendum on Republican Gov. Scott Walker, a villain in the eyes of many local Democrats.

It’s an obvious bid to rile up the party’s rank-and-file, said Kanninen, but it’s also an easy way to get independents to pay attention.

“Folks that would think of themselves as independent there are probably pretty progressive,” he explained, noting the attractiveness of Sanders-style ‘movement’ politics to the types of voters who unsuccessfully recalled Walker in 2012. "There was a healthy Green Party candidate a few years back, and the college student angle is so big: in most states they’d have to register with a party, with so many hurdles. And they don’t have that in Wisconsin.”