Democrats and elected officials have long argued that a Wisconsin voter identification law allowed Donald Trump to win the state in 2016 by keeping thousands of voters from the polls. A top Republican official has now asserted the same.

Wisconsin Attorney General Brad Schimel, who defended the voter identification law in court, told conservative radio host Vicki McKenna Thursday, “We battled to get voter ID on the ballot for the November ’16 election. How many of your listeners really honestly are sure that Sen. [Ron] Johnson was going to win reelection or President Trump was going to win Wisconsin if we didn’t have voter ID to keep Wisconsin’s elections clean and honest and have integrity?”

Mother Jones reports:

The law, which went into effect in 2016, required specific forms of government-issued photo identification to vote. In a cover story last year, Mother Jones reported that the law kept tens of thousands of eligible voters from the polls and likely tipped the state to Trump. A federal court found in 2014 that 9 percent of registered voters in Wisconsin did not possess the identification necessary to vote. In a University of Wisconsin study published in September 2017, 1 in 10 registered voters in Milwaukee County and Madison’s Dane County who did not cast a ballot in 2016 cited the voter ID law as a reason why. That meant that up to 23,000 voters in the two heavily Democratic counties—and as many as 45,000 voters statewide—didn’t vote because of the voter ID law. Trump won the state by 22,000 votes. African Americans, who favored Hillary Clinton over Trump by an 88-to-8 margin, were three times as likely as whites to say they were deterred from voting by the law.

Voter turnout indeed fell most dramatically in Milwaukee’s black neighborhoods, which were expected to vote for Clinton. Nearly 41,000 fewer people in Milwaukee voted in 2016 than in 2012. Rolling Stone reports that while Wisconsin ranked second in the nation in voter participation in 2008 and 2012, the state saw a 3.3 percent drop in voter turnout in 2016—the largest decrease of any state other than Mississippi. About half of the decrease occurred in Milwaukee.

Neil Albrecht, executive director of the Milwaukee Election Commission, told Mother Jones, “It is very probable that between the photo ID law and the changes to voter registration, enough people were prevented from voting to have changed the outcome of the presidential election in Wisconsin.”

Republicans asserted that the voter ID laws were necessary to prevent fraud, though voter fraud is rare in Wisconsin and nationwide: According to one major study, there were only 31 cases of voter impersonation out of more than 1 billion votes cast between 2000 and 2014.

Mother Jones continues:

Though Schimel said the law would “keep Wisconsin’s elections clean and honest,” the state didn’t present a single case of voter impersonation in court that the law would have stopped. The law remains in effect for the 2018 elections and could once again boost Republicans running for reelection, including Schimel and Wisconsin Gov. Scott Walker.

Walker disagreed with Schimel’s suggestion that the voter ID law enabled Johnson to win re-election and Trump to win the state in the 2016 election. The Los Angeles Times reports:

Asked Monday whether he agreed with Schimel that voter ID made the difference for both candidates, Walker told reporters that Johnson worked “his tail off” on the campaign trail and made a “great connection” with voters. As for Trump, Walker said it was clear people weren’t happy with Hillary Clinton because she didn’t visit the state after the primary and Trump connected with people who felt ignored.

Republicans have also been accused of gerrymandering by manipulating Wisconsin voter district boundaries. In November 2016, a federal court panel struck down Wisconsin’s state legislative maps as “an unconstitutional political gerrymander” that was “intended to burden the representational rights of Democratic voters … by impeding their ability to translate their votes into legislative seats.”