WASHINGTON, D.C. — A new Democratic analysis suggests the party’s eventual 2020 presidential nominee has an overlooked opportunity to win over voters in rural America, potentially halting a decadelong slide with a slice of the electorate that has shifted decisively toward the GOP.

The analysis itself is replete with caveats and faces deep skepticism from top Republicans and even some Democrats, who doubt President Donald Trump is losing ground in a region of the country that includes his most devoted supporters. But it might nonetheless reshape the common understanding of how Democrats can win next year’s presidential election — and points to a possible vulnerability for Trump and the GOP.

The Democratic analytics firm Catalist recently published a review of the 2018 midterm elections using data gleaned from voter files, a state-by-state report that offers the most detailed look yet at turnout in last year’s races.

The findings were startling: When comparing the 2016 presidential election to 2018 House races, the biggest increase of support for Democrats came not in the suburbs (which received the most attention) but in rural areas.

According to the analysis, Democrats recovered slightly more than half the vote in rural areas that they lost between 2012 and 2016, a net gain of about 6 percentage points in the region. By comparison, Democratic gains in suburban areas were roughly a point or two lower.

“Rural America has become heavily Republican in recent years, but the 2018 results do offer a glimmer of hope for Democrats,” said Yair Ghitza, who wrote the study and is Catalist’s chief scientist.

Crucially, in data Catalist provided to McClatchy, the shift in rural America was in large part because voters who didn’t support Democrats in 2016 switched their allegiance two years later, a dynamic present in other parts of the country as well, the analysis found. The party’s vote share increased by 5 points, from 30% to 35%, among rural voters who voted in both elections, gains that were concentrated among younger and single white voters.

In other words, the change in rural America’s electoral margins didn’t occur only because Trump’s core supporters stayed home on Election Day — the shift happened because voters changed their minds after 2016 and, consequently, might be inclined to continue to support the next Democratic presidential nominee in 2020.

Ghitza offered a series of caveats about the analysis, including that voter attitudes can — and often do — change from presidential to midterm elections, only to snap back in the next presidential race. Voting for a Democratic presidential candidate is also different than voting for a Democratic House candidate, the latter of whom has local ties and could present a more moderate agenda and message.

“It will be interesting to see what happens with Trump back on the ballot, but rural areas remain important if Democrats are going to continue and build upon their success in 2020,” Ghitza said.

The GOP’s vulnerability with rural voters was concentrated among younger white voters and unmarried white voters, Catalist found.

In 2016, for example, Trump won an overwhelming share of white rural voters under 30, receiving 58% of their vote while just 27% of them backed Democrats (another 15% backed neither Trump nor Hillary Clinton). In 2018, however, the Democratic share of these voters jumped 13 points, with Democrats winning 40% of them compared to the GOP’s 58 percent.

The increase for Democrats was even larger among rural white voters between the ages of 30 and 44: In 2016, Trump won 66% of those voters, while Democrats won just 23% of them (another 11% backed a different candidate). But two years later, Democrats won 35% of these voters, while Republicans won 63% of them —a 15-point swing.

(Ghitza said although some of the increased Democratic support comes from people who voted “other” in 2016, his own analysis suggests it also includes a substantial number of voters who backed Trump.)

Democrats also made sizable gains with single white men and women, cutting into the GOP’s edge with men by 13 points and with women by 15 points.

Voters who switched their political allegiance in 2018 would figure to be prime targets for the eventual Democratic presidential nominee. If they were willing to cast a vote against the GOP in a midterm, the thinking goes, they’re likely to at least consider doing so again in the 2020 presidential election.

And in the event that most do return to Trump, even small declines of rural support for a president who won narrowly in 2016 would seriously undermine his reelection campaign.

But leading Democratic strategists — even those who think the party has a genuine chance to cut into Trump’s margins in rural America — say any opportunity to win over rural voters will depend on a commitment from the party to compete in those parts of the country.

Since Clinton’s defeat, Democrats have debated whether the party should emphasize reaching out to Trump voters or mobilizing their own electoral base. For many activists, trying to win over Trump supporters is a waste of resources for a voter bloc in lockstep support of the president.

Democrats who see a way to make inroads in rural regions say this mindset is a mistake.

“There’s an opportunity to improve there, but we have to connect and we have to commit,” said J.B. Poersch, president of Senate Majority PAC. “There have to be resources at the table here.”

Still, Democrats have reason to think that votes in rural America will be hard to come by — even if voters did signal an openness to their party last year.

For one, a contentious Democratic presidential primary could damage the eventual nominee’s standing with these voters, or push them too far left to effectively win them over. Presented with an unappealing Democrat on the ticket, voters who swung against the GOP in 2018 might be inclined to support Trump again in 2020.

GOP strategists pointed out that Barack Obama suffered a humiliating defeat in the 2010 midterms only to win re-election relatively easily two years later.

“It is either just spin or wishful thing to try and extrapolate things that happened in 2018 and apply them to 2020,” said Mike Shields, a Republican strategist and senior adviser to Data Trust, which is the central clearing house of voter information for the GOP.

Shields said that according to his data, Trump’s standing with rural voters has only strengthened since 2016.

Of concern to even Democrats was the fact that, per a review of the data, there was less movement away from the GOP in states where Trump was most engaged last year, like Florida or Georgia. Trump will engage to the fullest everywhere during his reelection campaign, they say.

“It’s a real concern,” said Matt Canter, a Democratic strategist. “At the end of the day, that dynamic swamped us in Florida and swamped us in Ohio. So I think it’s a real concern in places like Pennsylvania and Wisconsin.”