This week, courts issued decisions on voting restrictions in two states that could decide which party controls the Senate after the upcoming midterm elections — ruling against restrictions in Missouri but in favor of them in North Dakota.

In Missouri, a judge on Tuesday ruled that the state can’t tell voters they need an ID with a photo to vote, because the state technically allows other IDs. “No compelling state interest is served by misleading local election authorities and voters into believing a photo ID card is a requirement for voting,” Cole County’s Senior Judge Richard Callahan said.

Studies have found that stricter photo ID requirements can benefit Republicans, because minority voters more likely to vote for Democrats are often less able to get the specific IDs demanded by such laws.

The state said it will appeal the ruling.

In North Dakota, the Supreme Court on Tuesday allowed a lower court ruling that lets the state enforce its voter ID requirement. The rule asks voters to present a current residential address to vote, but Native Americans living on a reservation — potentially thousands who are more likely to vote Democrat — don’t have a typical residential address, instead relying on PO boxes. As Huffington Post reporter Kevin Robillard noted on Twitter, many Democrats say the law “was explicitly passed in reaction to [Sen. Heidi] Heitkamp’s upset win in 2012.”

Democratic senators are currently facing tough reelection bids in both states, according to RealClearPolitics’ polling average. In North Dakota, Heitkamp is down by a whopping 8.7 points against her Republican challenger Kevin Cramer. In Missouri, Democratic Sen. Claire McCaskill is down 0.4 points against Republican challenger Josh Hawley. With control of the Senate expected to come down to as little as one or two seats, losing either election could doom Democrats’ chances of controlling the legislative body.

It’s unclear just how big of an effect the latest rulings will have. The decision in Missouri could be good news for Democrats, and the ruling in North Dakota could be bad for them. Since studies suggest that voter ID requirements swing turnout by a few points at most, that all comes with the caveat that the elections have to be fairly close — which is definitely true in Missouri but not so much in North Dakota right now, based on polling — for voter ID requirements to have a significant impact.

But this is part of the Republican plan: Over the past few years, GOP lawmakers took advantage of their victories in state legislatures to enact all sorts of new restrictions on voting to give themselves an advantage, however slight, in elections to come.

Republicans are creating more barriers to the voting booth

According to the Brennan Center for Justice, 23 states, predominantly controlled by Republicans, have enacted new voting restrictions since 2010: “13 states have more restrictive voter ID laws in place (and six states have strict photo ID requirements), 11 have laws making it harder for citizens to register, six cut back on early voting days and hours, and three made it harder to restore voting rights for people with past criminal convictions.”

Since the 2016 election in particular, Arkansas and North Dakota approved new voter ID laws. Missouri has implemented new voting restrictions that were approved by voters via ballot in 2016. And several other states — Georgia, Iowa, Indiana, and New Hampshire — passed new restrictions on top of those they had before, according to Brennan.

Republican supporters of the restrictions argue that they’re meant to prevent voter fraud. For example, a photo ID requirement is supposed to make it more difficult for someone to impersonate another voter on Election Day.

But voter fraud is extremely rare in the US.

Loyola Law School professor Justin Levitt studied voter impersonation. He found 35 total credible accusations between 2000 and 2014, constituting a few hundred ballots at most. During this 15-year period, more than 800 million ballots were cast in national general elections and hundreds of millions more were cast in primary, municipal, special, and other elections.

A 2012 investigation by the News21 journalism project looked at all kinds of voter fraud nationwide, including voter impersonation, people voting twice, vote buying, absentee fraud, and voter intimidation. It confirmed that voter impersonation was extremely rare, with just 10 credible cases.

But the other types of fraud weren’t common either: In total, the project uncovered 2,068 alleged election fraud cases from 2000 through part of 2012, covering a time span when more than 620 million votes were cast in national general elections alone. That represents about 0.000003 alleged cases of fraud for every vote cast, and 344 fraud cases per national general election, in each of which between 80 million and 135 million people voted. The number of fraudulent votes was a drop in the bucket.

What’s more, not all — maybe not even half — of these alleged fraud cases were credible, News21 found: “Of reported election-fraud allegations in the database whose resolution could be determined, 46 percent resulted in acquittals, dropped charges or decisions not to bring charges.”

This has made Democrats very suspicious of Republicans’ push for more voting restrictions.

Studies suggest that the voting requirements Republicans have pursued disproportionately hurt minority voters who are more likely to elect Democrats. A widely cited 2006 study by the Brennan Center found voter ID laws, for instance, disproportionately impacted eligible black voters: 25 percent of black voting-age citizens did not have a government-issued photo ID, compared with 8 percent of white voting-age citizens. And a study for the Black Youth Project, which analyzed 2012 voting data for people ages 18 to 29, found 72.9 percent of young black voters and 60.8 percent of young Hispanic voters were asked for IDs to vote, compared with 50.8 percent of young white voters.

One reason for these kinds of numbers is disparate enforcement. Polling officials, perhaps driven by racial biases, appear more likely to ask minority voters for an ID.

But minority voters are also generally hit harder by voter ID laws and other restrictions on voting. For example, since minority Americans are less likely to have flexible work hours or own cars, they might have a harder time affording a voter ID or getting to the right place (typically a DMV or BMV office) to obtain a voter ID, rely more on early voting opportunities to cast a ballot, or require a nearby voting place instead of one that’s a drive, as opposed to a walk, away from home or work.

In fact, some Republicans have outright acknowledged that hurting Democratic voters is their goal. As William Wan reported for the Washington Post, following the passage of and court challenges against North Carolina’s controversial law:

Longtime Republican consultant Carter Wrenn, a fixture in North Carolina politics, said the GOP’s voter fraud argument is nothing more than an excuse. “Of course it’s political. Why else would you do it?” he said, explaining that Republicans, like any political party, want to protect their majority. While GOP lawmakers might have passed the law to suppress some voters, Wrenn said, that does not mean it was racist. “Look, if African Americans voted overwhelmingly Republican, they would have kept early voting right where it was,” Wrenn said. “It wasn’t about discriminating against African Americans. They just ended up in the middle of it because they vote Democrat.”

So despite claims that this is really about the integrity of elections, enough Republican supporters have slipped in moments of candor to validate Democrats’ suspicions — that this is about stifling the fundamental right to vote for constituents that Republicans don’t typically win.

Will this impact the midterm? It depends how close the races are.

One silver lining for Democrats: The new voting restrictions may not have a huge impact on elections.

That might be surprising, considering all the headlines about voter ID laws in the past few years. A 2012 analysis, for example, found that as many as 758,000 registered voters in Pennsylvania don’t have a photo ID issued by the state’s Transportation Department — meaning that up to 9.2 percent of Pennsylvania voters may have been disenfranchised by a strict photo ID law.

But as Nate Cohn explained in a review of the evidence for the New York Times, figures like Pennsylvania’s are misleading. He cited a study for the North Carolina Board of Elections:

To begin with, the true number of registered voters without photo identification is usually much lower than the statistics on registered voters without identification suggest. The number of voters without photo identification is calculated by matching voter registration files with state ID databases. But perfect matching is impossible, and the effect is to overestimate the number of voters without identification. … People without ID are less likely to vote than other registered voters. The North Carolina study found that 43 percent of the unmatched voters — registered voters who could not be matched with a driver’s license — participated in 2012, compared with more than 70 percent of matched voters.

Essentially, the number of voters who don’t actually have an eligible ID is very inflated by estimates like Pennsylvania’s. And assuming that these people will vote in the first place is a mistake; they’re less likely to vote, with or without a voter ID law.

Cohn added:

There’s no question that voter ID has a disparate impact on Democratic-leaning groups — those young, nonwhite, poor, immobile or elderly voters. The unmatched North Carolina voters were registered as Democrats by a 37-point margin, compared with the 12-point Democratic margin statewide. They were 46 percent nonwhite, compared with 29 percent of all registered voters. But 22 percent of these voters were registered Republicans. The voters without an identification might be breaking something more like 70/30 for Democrats than 95/5.

As Cohn wrote, a 70-30 skew is still a big loss for Democrats. But when taking into account that many of these people are unlikely to vote in the first place, the total count of lost voters is much smaller than one would think.

Studies looking into voter ID laws’ effect on voter turnout back this up. The research, including multiple studies conducted over several years, has generally found that voter ID laws have little to no impact on voter turnout, even when looking at specific racial groups.

So while voter ID laws probably hit Democratic and minority voters harder than their Republican and white counterparts, we’re really talking about a small effect here. The laws could only swing the closest of elections.

None of the other voting restrictions enacted by states seem to have much of an effect on voting either. For example, researchers have found mixed effects on whether early voting increases turnout, with one recent study finding that it actually decreased turnout on net if voters couldn’t register to vote and cast their ballot on the same day.

No study has the final word, but the research is generally close enough to suggest that practical barriers to voting have a fairly small effect on whether people actually vote.

The bad news for Democrats is that some of the elections they’re facing in November are expected to be really close. That includes the Missouri Senate race, which could very well come down to less than a percentage point between the Democrat and the Republican. So any impact from voting restrictions could very well decide that state’s race — and therefore control of the Senate — in Republicans’ favor.