Rachel Kiefer is a Marquette University Golden Eagle through and through, but until recently her driver's license said Connecticut. 

A college sophomore living in Milwaukee, Kiefer swapped her home state ID for a Wisconsin one so she could vote in the Badger State's presidential primary. Her regular student ID card wasn't up to the standards spelled out in Wisconsin's new voter ID law — one of the strictest in the country. Kiefer said she's worried her peers, particularly those from out of state, might not realize that and head to the polls unprepared on Tuesday. 

"I don't know how aware people are," said the 19-year-old field coordinator for Marquette's College Democrats chapter.

Wisconsin had the second-highest youth turnout rate in the nation in the 2012 general election, but getting college students to vote Tuesday might prove challenging. Many IDs from higher education institutions either don't qualify or demand students bring additional paperwork to the polls, complicating voting for young adults without in-state driver's licenses, easy access to personal documents or knowledge of the political process. Experts said voter ID legislation in effect in Wisconsin and 32 other states could particularly hurt candidates like Sen. Bernie Sanders, who relies on young people and has recently denounced the law. It could also possibly foretell issues with national youth turnout in November.

"There's been a little bit of confusion on campuses around which regular student IDs work for voting and which don't," said Joe Zepecki, a Democratic strategist based in Milwaukee. Despite various volunteers' and administrators' efforts to spread awareness about the law, he said, "There's no doubt in my mind that there are going to be students [Tuesday] who don't get the opportunity to cast a ballot or have a difficult time casting a ballot in terms of these restrictions."

An estimated 300,000 people could be blocked from voting in Wisconsin as a result of a 2011 law that mandates all voters must have acceptable photo IDs to cast ballots. The regulation is aimed at preventing fraud but can pose problems for groups who can't afford or don't have access to the documents needed to obtain the IDs. Among those especially affected are low-income residents, minorities and youth, MSNBC reported. College students in particular often don't have IDs that reflect their current address.

Tuesday will be the first major election in Wisconsin since the United States Supreme Court upheld the law last year. Worth 86 delegates for the Democrats and 42 for the Republicans, the state's primaries could cement the leads of front-runners Donald Trump and Hillary Clinton or make way for underdogs like Sanders, I-Vt., Ohio Gov. John Kasich and Sen. Ted Cruz, R-Texas.

In order to participate, voters must show valid ID, examples of which include state driver's licenses, passports, military ID cards and naturalization certificates. They do not include student IDs without a signature, issue date and expiration date or ones presented without additional proof of enrollment. According to the Nation, this means the polls will accept only standard IDs from students at 10 of a 36-campus group including the University of Wisconsin system and some private colleges. If a voter can't provide ID, he or she can fill out a provisional ballot.

Schools like the University of Wisconsin-Madison, where nearly a quarter of students were nonresidents, launched campaigns to advertise the law and accommodate students by issuing free voter ID cards in their student unions. Kiefer said Marquette officials partnered with student clubs for registration drives and sent out a campuswide email last week telling people what they need to vote.

"We're trying out best to let people know about it," said Zachary Druckrey, the 21-year-old media and communications director of Badgers for Bernie at the University of Wisconsin-Madison. "The whole thing's real messy and weird and it's really getting to a point where it's kind of obvious to us why it's there: It's there to make voting harder."

In 2012, under-30 voters turned out at a rate of about 58 percent in Wisconsin, voting for President Barack Obama by a 23-percentage-point margin. At a national level, half of millennials identify as independent — but have voted largely Democratic in the past two elections, according to Pew Research Center.

Some candidates stand to benefit more from youth engagement than others. Sanders, for example, has enjoyed a passionate millennial following both nationwide and in the Badger State, where a Marquette poll found Sanders had the support of 83 percent of likely Democratic primary voters between ages 18 and 29. Clinton had 12 percent.

Sanders has spent the past few days vocally disagreeing with Wisconsin's voter ID law, attacking Republican Gov. Scott Walker for signing what he calls "voter suppression" into law. 

"I think what Gov. Walker and what other Republican governors and legislators are doing is not only shameful, it's un-American in the deepest sense of the word," the Hill reported Sanders said at a Sunday rally. "Trying to figure out ways, 'Gee, senior citizens may vote against me, how do I make it harder for them to participate? Young people may vote against me, how do I make sure that many of them will not vote?' "

Paul Maslin, a Democratic strategist in Madison, said he didn't think the voter ID law would swing too many votes from Sanders to Clinton. Sanders' refrain that "we do not do well when the voter turnout is not large" hasn't been backed up with much evidence, Maslin said, because the voter ID law also hurts minorities and senior citizens as well — groups Clinton consistently wins over the senator.

For Sanders, "it's a rhetorical tool that helps with his overall message ... it's not clear that it actually generates more turnout," Maslin said.

One area it could impact is future voting. Maslin said studies have established that casting ballots is habitual, and the Wisconsin law could discourage young people from getting involved in politics. 

"There's danger here of people who, because of this law, don't get started in the process and then are essentially somewhat disenfranchised from the get-go," he added. "And those votes are going to tend to be more liberal, Democratic than Republican."

That applies to students as well as low-income youth and those who aren't pursuing higher education, said Abby Kiesa, a youth coordinator and researcher at the Center for Information and Research on Civic Learning and Engagement at Tufts University in Medford, Massachusetts. It also applies outside of Wisconsin: The National Conference of State Legislatures lists 33 voter ID laws in effect in states like Texas, Tennessee, North Dakota, Indiana and Virginia.

"Generally, I would say that this is not just a Democratic issue with a big 'D.' It's a small-'d' democratic issue for the country," Kiesa said. "For the sake of democracy, people should be caring about access and building a new generation for whom there's a habit to vote and participate in their community."