Wisconsin governor Scott Walker leads Democratic challenger Mary Burke 47–46 percent among likely voters, according to a new poll from Wisconsin Public Radio and St. Norbert College. Walker’s lead expands to three percentage points among registered voters, while 11 percent of voters surveyed remain undecided. Walker has trailed or tied Burke in three previous polls, and the newest survey only confirms that the race will likely be just as close on Election Day.

Voter turnout and the still-undecided voters could decide the election if Walker and Burke remain tied in the polls, which puts the spotlight back on the decision of the U.S. Supreme Court to block Wisconsin’s voter-ID law from taking effect before November. The Court made its decision without much explanation, but opponents of the law raised concerns that some mail-in votes would not get counted unless the voters showed up to verify their identities. The Court’s decision did not decide the law’s ultimate fate, but the law’s injunction could mean that illegitimate votes shape the outcome of the election.