DES MOINES, Iowa — The two dozen Democrats seeking the party’s presidential nomination have found few applause lines more likely to earn a standing ovation than a pledge to overhaul campaign finance rules.

Now, Montana Gov. Steve Bullock (D) is putting the Supreme Court’s Citizens United v. FEC decision at the center of his long-shot bid for the Democratic presidential nomination.

The decision, and the resulting influx of outside and undisclosed money, is what Bullock sees as the hurdle that stands in the way of every other item on the progressive wish list.

“I’ve done more work than anybody else in the field on the one issue that’s holding us back from everything else, from giving folks a fair shot in the economy to climate to everything else, and that’s addressing the corrupting influence of dark money in our elections,” Bullock told The Hill as he launched his presidential campaign last week.

Meeting Iowa voters at a brewery here, Bullock recounted the campaign finance battles he had won — robust reporting requirements passed through his Republican-led legislature and an executive order requiring state contractors to disclose dark money contributions — and one he had lost, a Supreme Court case that ultimately struck down Montana’s century-old ban on corporate spending in elections.

“We’re seeing firsthand the amount of dark money coming into our system,” Bullock told voters. “We see tax laws being written for the wealthy. We see environmental laws being gutted for the polluters. No wonder people are frustrated. No wonder they’re anxious.”

Bullock, 53, was one of only three Democrats to win gubernatorial races in states that voted for President Trump in 2016. Montana favored Trump over Democratic nominee Hillary Clinton by 20 points; Bullock won 75,000 more votes than did Clinton.

That may be appealing to Iowa Democrats, who have struggled in statewide elections in one of the most rural states in the country. Democrats have held the governorship for just 12 of the last 50 years, and Republicans now control both of the state’s Senate seats. Democrats made gains in 2018, picking up two House seats and several state legislative seats, largely in Des Moines’s western suburbs.

“The urban-rural divide is growing even faster than before,” said Sean Bagniewski, who chairs the Polk County Democratic Party.

Bullock will make his ability to win crossover voters in his mostly rural state a cornerstone of his appeal to Democratic primary voters and caucusgoers, starting in Iowa, one of the most rural states in the country. Six of Bullock’s eight stops on a weekend swing through Iowa came in counties Trump won in 2016.

To reach those voters, Bullock does not plan a sprint to the left to compete with other better-known candidates who have staked out more liberal positions. Asked whether he backed the Green New Deal offered by Rep. Alexandria Ocasio-Cortez (D-N.Y.), Bullock said other approaches to combating climate change should take priority.

“I’m glad that the Green New Deal is out there as a discussion. You get people talking about bold measures that need to be taken,” Bullock said. “It’s great from an aspirational, get people talking about it. But if you look at the specifics, I think there are other things we can do.”

In 2016, Bullock was critical of Clinton’s pledge to put coal miners out of business.

“Being pro-worker does play, and we shouldn’t be saying we’re going to be putting anybody out of business along the way. Fundamentally, look, you can turn around and say there have been more coal utilities that have closed under Donald Trump than all eight years under President Obama,” he said. “We all know that we need to address climate, and we’ve been taking steps in Montana.”

And he said he would not support a single-payer, “Medicare for All” system.

“I support accessibility for everyone, affordability for everyone. That’s what we’ve been working on,” he said. “I think we can get to access and affordability without disrupting 70 percent of America that has private health insurance. So I would do a public option. I would turn around and say it’s time we start negotiating drug prices.”

At a time when partisan rancor in Washington has ground legislating to a halt, Bullock will point to a record built in partnership with a Republican majority in the state legislature. Earlier this month, he signed a measure extending Medicaid expansion for another six years, a compromise bill that included work requirements necessary to win over Republican votes.

“We are more divided now than any time in my lifetime. Forget about cable news, forget about Twitter, we can’t even have a conversation at Thanksgiving dinner without politics dividing us,” he said. “I fundamentally believe, even in this time of great division, that government can work.”