Lawmakers in several states this year changed or erased voter-approved ballot measures. While some officials are pushing to make it harder to pass future such initiatives, people in a few states have been scrambling to protect them from legislative tampering.

Here's a look at some of the areas where the power struggle between citizens and their politicians is occurring:

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MAINE

A legislative government accountability office is reviewing Maine's citizen initiative process. Lawmakers could consider changes including raising the threshold to get on the ballot.

A Democratic senator in October proposed to safeguard ballot initiatives for a year after their passage, but the effort was unsuccessful. He plans to try again.

Lawmakers have recently brushed aside several voter initiatives. They eliminated a surcharge on high-income earners for education and rolled back a minimum wage measure. They also delayed a ranked-choice voting law until 2021; it would then be repealed unless the state constitution is amended to allow it.

Supporters are mounting a "People's Veto" referendum campaign.

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MISSOURI

A proposed constitutional amendment would ban the Legislature from changing or repealing any approved ballot measures without going back to voters. Supporter Winston Apple said backers have had trouble getting people to help gather signatures for the plan.

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NORTH DAKOTA

The Legislature approved a commission this year to review the initiative process and the cost of placing them on the ballot

It was spurred largely by voters' approval of medical marijuana and a different measure financed solely by a California billionaire that incorporated victims' rights provisions into the state constitution.

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OHIO

A Republican lawmaker is after a constitutional change to make it more difficult for voter initiatives to reach the ballot and ultimately win approval.

Rep. Niraj Antani says Ohio must take steps to "remove the 'for sale' sign" currently on its constitution and laws, criticizing out-of-state special interest groups.

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SOUTH DAKOTA

Voters could face divergent proposals on the 2018 ballot.

A proposed constitutional amendment would stop lawmakers from changing future ballot measures and the state's initiative system without taking the changes to a public vote.

Meanwhile, a Republican legislator is pushing an initiative that would ban out-of-state political contributions for ballot questions, and some lawmakers want to ask voters to make it harder to change the state constitution.

The choices would come after Republicans this year repealed a government ethics overhaul that voters approved in 2016.