(CNN) There are still a few states where Republican governors and lawmakers refuse to expand Medicaid. But residents may force their hands at the polls in November.

Voters in Utah, Idaho and Nebraska will decide whether to accept the Affordable Care Act's Medicaid expansion provision, while those who live in Montana will vote on whether to maintain the expansion beyond July 2019.

The ballot measures come a year after Maine's residents gave the thumbs up to expansion by a 59% to 41% margin in a first-of-its-kind referendum. However, it has yet to go into effec t there as Republican Governor Paul LePage continues to resist implementing it . The Maine Supreme Judicial Court last week ordered the governor to submit an expansion plan to the federal government.

Some 31 states plus the District of Columbia have already expanded Medicaid, which broadens coverage to Americans with incomes up to 138% of the poverty level, or about $17,000 for an individual and $35,000 for a family of four. Virginia will join the club in 2019, after lawmakers there approved expansion earlier this year.

The victory in Maine buoyed efforts in other red states, where activists were already organizing.

"We found a new strategy for expanding Medicaid in states where politicians simply refuse to ... going over their heads and straight to voters," said Jonathan Schleifer, executive director of The Fairness Project, which provides funding and guidance to grassroots campaigns.

To get on the ballot, advocates in each state had to gather tens of thousands of signatures. Early polls show voters back expansion, they say.

The campaign in Idaho began when two high school friends and one's wife toured the state last summer in a bright green 1977 Dodge camper -- with "Medicaid for Idaho" emblazoned on the side. They were trying to raise support for Medicaid expansion by talking about those who earn too much to qualify for the safety net program but can't afford coverage on the Obamacare exchanges. The trio, along with many volunteers, collected double the 56,000 signatures needed, said Emily Strizich, co-founder of Reclaim Idaho, which led the effort.

Three Idaho residents traveled the state last summer to raise support for Medicaid expansion.

"We realized there is a lot of energy around health care," she said. "So many people had a parent, sibling or co-worker fall into the coverage gap."

Some 91,000 residents would qualify for coverage if Idaho expands, and the state will receive $368 million in federal funds for expansion in fiscal 2021, its first full year, said Strizich, citing an actuarial report done for the Idaho Department of Health and Welfare. (The federal government picks up at least 90% of the tab.)

In Utah, where past attempts to expand Medicaid failed in the state's lower chamber, organizers had only three months to gather at least 113,000 signatures. They easily cleared that bar by going to community events, knocking on doors and turning to social media, said RyLee Curtis, campaign manager for Utah Decides Healthcare. The group will start running television and radio ads next month in hopes of convincing voters to support the measure at the polls.

Utah residents will decide whether to expand Medicaid in November.

Advocates are calling attention to the fact that 150,000 residents will gain coverage, and Utah will receive $800 million in federal funds for expansion annually, Curtis said. The ballot measure also calls for raising the sales tax on non-grocery items by 0.15% to pay for the state's 10% share of the expansion.

"This campaign is about letting Utahans decide," Curtis said. "It transcends politicians."

Nebraska organizers also collected far more signatures than they needed using similar tactics. Some 90,000 residents will gain coverage, more than two-thirds of whom work but their jobs don't provide health insurance, said Meg Mandy, campaign manager for Insure the Good Life, which is promoting expansion in the Cornhusker State. Also, expansion will bring the state $1.1 billion in federal funding over four years and sustain 10,000 jobs, many of which are in rural areas.

The ballot measures do have their opponents. In Nebraska, a Republican state senator and a former legislator unsuccessfully challenged the expansion initiative in court. The Idaho Republican Party passed a resolution in June opposing the ballot measure.