Rep. Austin Knudsen, R-Culbertson, leads a Republican party news conference Thursday Jan. 9, 2014, on the first day to file for public office in the Montana state capitol, as a great way to get fired up for the election season in Helena, Mont. The Democratic party held a similar “rally” earlier in the day as both parties officially filed with the Secretary of State, Linda McCulloch. (AP Photo/The Independent Record, Eliza Wiley)

Montana voters will decide this November whether to continue allowing new voters to register on Election Day after the state Supreme Court ruled a legislative referendum could proceed.

The court on Wednesday denied a petition from labor and voting-rights groups to block the referendum from the fall ballot.

The Republican-controlled legislature passed the referendum in 2013, placing it on the 2014 ballot. Opponents argued that language in the referendum’s ballot title, which initially asserted that ending same-day voter registration was required to comply with federal law, was misleading.

In the 5-1 decision, the state Supreme Court said Montana Attorney General Tim Fox (R) must rewrite the ballot title to clarify that language. Ending same-day registration is not required by the National Voter Registration Act, as the referendum initially asserted.

Montana voters have been able to register on Election Day since 2006. Republicans have complained that same-day registration can open an election to fraud, though only a few cases of fraud have ever been uncovered. Democrats and voting rights groups say there is no better way to boost turnout than to allow same-day registration.

Montana’s law already contains fraud-prevention measures. Voters who register on Election Day must do so at county election offices, not at polling places. And any new registrant who cannot meet the state’s identification requirements must cast a provisional ballot, then return within three days to show proper identification before the ballot is counted.

The proposed referendum would end registration at 5 p.m. on the Friday before Election Day.

Ten states and the District of Columbia currently allow same-day voter registration, according to the National Conference of State Legislatures. Voters in Maine, Minnesota and Wisconsin have been able to register on Election Day since the mid-1970s, while a handful of blue states — California, Colorado and Connecticut — have begun allowing the practice in just the past two years.

The fight over Montana’s law is one of two referenda that will head to the ballot this year. Unions and Democratic groups have sued over another measure, Legislative Referendum 127, that would institute a so-called “top-two” primary system, in which the two highest vote-getters in a primary move on to a general election, regardless of party affiliation.

Groups that oppose the top-two primary say the 198-word ballot title violates state rules that impose a 100-word limit on those titles. The state Supreme Court has not ruled on Referendum 127 yet.

Three other states, Washington, California and Louisiana, use some form of the top-two process. Republicans in Montana hate the current system, in which nominees from all parties reach the November ballot, because Libertarian candidates can siphon off votes that would otherwise likely go to the GOP nominee.

A top-two system, Republicans believe, would have allowed the party to capture a U.S. Senate seat in either 2006 or 2012. In both years, Sen. Jon Tester (D) won election with less than 50 percent of the vote. In 2006, Tester beat incumbent Conrad Burns (R) by 49 percent to 48 percent, with a Libertarian candidate taking 2.5 percent of the vote. In 2012, Tester staved off Rep. Denny Rehberg (R) by three points; a Libertarian candidate took 6 percent of the vote that year.

Both measures passed the legislature in 2013 on party-line votes, with Democrats using procedural tactics to stall.