PIERRE, S.D. — South Dakota voters will decide in November if the state constitution should be harder to change.

The House of Representatives voted 55-9 Tuesday to send the constitutional amendment to the fall ballot. It asks voters to increase the majority vote threshold required for a constitutional change to 55 percent of the votes cast on the amendment.

Supporters say it’s designed to add an additional protection for the state constitution. Republican Sen. Jim Bolin, its sponsor, told a Senate panel last month that it’s a “legitimate and desirable method of protecting our fundamental political document.”

Democrats have opposed it. Critics contend the amendment could hamper direct democracy in South Dakota, which in 1898 became the first state in the nation to adopt citizen initiatives.

Republicans have discussed changes to the ballot question system after the 2016 election season brought 10 questions and millions of dollars from out-of-state groups.

The Legislature this session has proposed measures that would make it more difficult for voters to pass citizens’ initiatives and constitutional changes. A bill to restrict the flow of money from outside South Dakota into the state’s ballot question campaigns is scheduled to be debated in a Senate committee on Wednesday.

Others have been shelved, including measures that would have ended voters’ ability to bypass the Legislature to amend the state constitution and required ballot measure campaigns to collect signatures from a majority of state Senate districts when gathering names to qualify for the ballot.

Meanwhile, supporters of new constitutional protections for ballot measures are competing against the lawmakers who would curtail them.

The campaign for an amendment that would prevent the Legislature from altering or rejecting laws approved by voters has turned in enough valid signatures to put the question to November voters. The plan would also prevent lawmakers from changing the ballot question process without a public vote.