As the Trump administration rolls back Obama-era environmental regulations and continues to swipe at the Affordable Care Act, climate change and health care activists are focusing on state ballot initiatives around the country this Election Day. These measures are on the ballot as a result of citizen petitions, and some appear to have better chances of success than others do.

Voters in at least nine states on Tuesday will determine ambitious environmental measures, including an initiative to rein in greenhouse gas pollution in Washington that could be repeated in other states if successful as well as proposals to increase renewable energy standards in Arizona and Nevada. In four deep-red states residents will go to the polls to vote on Medicaid initiatives, a year after Maine became the first state to approve an expansion of the low-income health program via a citizen-driven ballot proposal. (Maine’s governor has refused to implement the expansion.)

Millions of dollars are being spent to sway voters, and several initiatives are pitting billionaire progressive donors pushing for climate change action against giant fossil fuel–producing corporations. Some of the renewable energy measures appear to be long shots whereas proposals to allow more people into Medicaid appear to have more voter support.

Here is a breakdown of initiatives on these three issues:

Washington State’s carbon emissions tax

Voters will decide whether to pass a first-in-the-nation carbon tax, and environmentalists are hoping for a precedent-setting result other states will follow to address climate change. Ballot Initiative 1631 would impose a tax on large emitters of carbon dioxide starting in 2020: $15 per metric ton of carbon generated. The cost would increase $2 a year after that, until Washington meets certain emissions targets. Revenue would be used for clean air and water projects.

Previous attempts to pass a carbon tax in the state legislature have faltered. And in 2016 a different carbon tax ballot initiative not only failed, but “divided the environmental community,” says Ed Bowlby, a retired marine biologist turned activist in western Washington. “We realize we don’t have a perfect solution, but this time we have something we can all get behind,” says Bowlby, one of 200 scientists and health policy experts to sign an open letter in support. “If this initiative happens to fail, we don’t have anything to fall back on.”

It has become the most expensive ballot initiative in Washington history: $45 million raised by forces pro and con. Microsoft founder Bill Gates and former New York Mayor Michael Bloomberg each gave $1 million to support passage. On the other side, the oil and gas industry has spent $30 million to defeat the measure. Opponents argue the carbon tax will exempt several large polluters and will lead to increased costs passed along to consumers and small businesses. “The more people know about Initiative 1631 the less they like it,” said Dana Bieber, a spokesperson for the No on 1631 coalition. And a recent Crosscut/Elway poll suggested the initiative is still a toss-up heading into Tuesday.

Renewable energy

In Nevada, Question 6 would “ensure that energy providers get at least 50 percent of their energy from renewable sources, like wind and solar, by 2030.” The effort is being funded by California billionaire Tom Steyer, and supporters say it will result in cleaner air and an influx of new green jobs.

A group of elected Republican officials have urged voters to reject the proposal, including the state’s controller, who said the measure would increase budget deficits. But Nevada’s longtime monopoly utility provider, NV Energy, is not opposing the measure. Proponents are hopeful. “We feel this has a strong chance of passing,” said Bill Holland, state policy director for the League of Conservation Voters, whose Nevada-based arm is involved in mobilizing support for the initiative.

Similar to Nevada’s ballot proposal, Arizona’s Proposition 127 would require electric companies to get half their energy from renewable sources like solar and wind by 2030. Steyer is also funding that push, donating $23 million. Unlike in Nevada, however, the state’s utility has aggressively opposed the idea: The utility, Arizona Public Service, has spent $30 million through a political action committee to defeat the measure. Opponents argue it is a job killer that will also increase electricity bills. A Suffolk University poll from late September showed only a third of voters supported the proposal. A more recent poll from an independent Arizona consulting firm suggested the measure appears “headed toward defeat.”

Medicaid expansion

Expanding Medicaid to include more low-income adults will be on the ballot in Idaho and Utah and Nebraska. Voters in Montana, which expanded Medicaid in 2015, will decide whether to continue the program beyond its 2019 expiration. A ballot initiative in that state proposes funding the continued program with a tobacco tax raising the price of a pack of cigarettes by $2. Tobacco companies have spent $17 million to oppose it.

In Idaho supporters gathered more than 56,000 signatures to get Medicaid expansion on the ballot, and are vastly outspending their opponents. They are funded in large part by a California health care workers union leading the Medicaid ballot effort in the other GOP-controlled state as well. The Idaho initiative recently got a bump from the outgoing governor, a Republican who publicly endorsed the initiative. It would cover up to 62,000 people.

Opponents have warned it would cost too much and allow more patients into an already crowded Medicaid system. Even if it passes, the “legislature would still have to figure out how to pay for it, and there’s going to be a very hard conversation given all of the state’s other spending priorities,” says Fred Birnbaum, vice president of the Idaho freedom Foundation, a libertarian think tank opposing the initiative.

Emily Strizich, a co-founder of Reclaim Idaho, a group that pushed the initiative, says state Republican leaders played politics by styming legislative attempts to expand the program. But she says “for people in rural Idaho working to make ends meet, they don’t think of this as a red-and-blue issue.” Strizich, who traveled around the state in a camper gathering signatures for the measure, says, “I hope on November 6 the people of Idaho have more common sense then their politicians have had.”