Voters in North Dakota on Tuesday backed a constitutional amendment that would impose age restrictions on congressional candidates.

The new measure bans people from running for a House or Senate seat in North Dakota “if that person could attain 81 years of age by December 31st of the year immediately preceding the end of the term.”

61% of voters on Tuesday approved the measure, while 39% opposed it.

It is believed to be the first-in-the-nation measure imposing age limits on candidates running for federal office, but it’s also expected to be challenged in court.

The measure, which doesn’t affect any of the current federal officeholders from North Dakota, comes as voters voice concerns about the ages of President Joe Biden, who is 81, and former President Donald Trump, who is turning 78 this week, as they each vie for another term as president.

There are currently three senators over 80: Senate Minority Leader Mitch McConnell and Sens. Chuck Grassley of Iowa and Bernie Sanders of Vermont. There are at least 10 members of Congress over 80, including former Speaker Nancy Pelosi and former Whip Steny Hoyer.

Republican Sen. Kevin Cramer, who is seeking his second full Senate term and won an unopposed primary in North Dakota on Tuesday, said he opposes the measure and believes that voters should get to vote for whoever they want, regardless of age.

“To limit those decisions arbitrarily just doesn’t make sense to me,” Cramer told the Associated Press.