On Friday, New Hampshire Republican Gov. Chris Sununu transformed his state into ground zero in the assault on voting rights. By signing HB 1264 into law, Sununu effectively imposed a poll tax on college students, compelling many of them to pay hundreds of dollars in fees to establish residence in the state before they’re permitted to vote in New Hampshire. Once it takes effect, the law is almost certain to chill the franchise of younger Democratic-leaning voters—to an extent that could swing the state’s famously close elections. But the measure’s stringent new requirements do not kick in until July 2019, giving Democrats a single opportunity to repeal it before it disenfranchises a key portion of their base. In New Hampshire, the November midterm elections won’t just determine control of the state government. It will decide whether Republicans will be successful in their years-long quest to suppress the college vote, a move that would help them further entrench their own political power.

HB 1264 is the latest and most sweeping voter suppression bill passed by New Hampshire Republicans in the wake of the 2016 election. Hillary Clinton carried the state by a slim margin, as did Democratic Sen. Maggie Hassan, who defeated incumbent Republican Sen. Kelly Ayotte by about 1,000 votes. At the same time, Republicans retook the governorship and maintained control of the Legislature, giving them total control of the state government. They used that power to begin restricting access to the ballot under the pretext of preventing voter fraud.

Donald Trump pitched in, alleging that thousands of Massachusetts residents were bused into cast illegal votes. So did his voter fraud czar, Kansas Secretary of State Kris Kobach, who falsely claimed to have “proof” of fraudulent voting in the state. Trump and Kobach were furthering a narrative endorsed by Sununu, who proclaimed before the election that “when Massachusetts elections are not very close,” Democrats are “busing them in all over the place.”

In response, Republicans launched a flagrant attack on the student vote. GOP legislators created their own voter fraud czar to investigate voters who registered on Election Day. (Same-day registration is perfectly lawful in the state.) It also passed a hugely controversial bill that allows state investigators and law enforcement officers to visit voters at their homes and demand proof that they live in the state. (Naturally, the bill’s Republican sponsor asserted that “people coming over the border” were swinging elections.) And now Republicans have passed HB 1264, a bill that’s the latest in a long line of GOP efforts to disenfranchise young voters in the state.

After the 26^thAmendment lowered the national voting age to 18 in 1971, New Hampshire declared it would deny the ballot to college students who might leave the state after graduating. A federal court forced the state to scrap this plan in 1972, holding the Constitution protects students’ right to vote where they live. Forty years later, the GOP-controlled state Legislature revived efforts to disenfranchise college students, passing a bill that inaccurately told new voters they could only register if they planned to live in New Hampshire indefinitely. The state Supreme Court unanimously invalidated the law in 2015.

What’s changed since then? Namely, the composition of the state Supreme Court. Sununu appointed two conservative justices to the five-member court and elevated a right-leaning Democratic appointee to the chief justiceship. Sensing a friendlier bench, Republican legislators pushed through HB 1264, which alters the residency requirements for New Hampshire voters. Previously, an individual need only be “domiciled” in the state to vote, meaning they resided in the state “more than any other place.” Under HB 1264, however, an individual must become a “resident” of New Hampshire to vote in the state.

The distinction between “domicile” and “residency” is entirely technical—a legal distinction exploited by the drafters of HB 1264 to single out student voters. Residency status triggers two obligations: Within 60 days of becoming a resident, an individual must get a New Hampshire driver’s license and register her car with the state. HB 1264 states that, by casting a ballot, a voter professes her intent to become a resident. Thus, students who moved to New Hampshire from elsewhere and brought their cars will have two months to fulfill residency requirements or risk incurring hefty fines.

Those requirements aren’t cheap. The cost of registering an out-of-state car can total several hundred dollars—hence the description of HB 1264 as a post-election “poll tax.” Car-driving students who wish to vote in New Hampshire, then, will have two options: Surrender their right to vote and remain “domiciled,” or exercise the franchise, become “residents,” and pay hundreds of dollars. If even a few hundred students decide that dealing with residency rules isn’t worth the hassle and legal risk, their absence could tilt elections away from Democrats.