The populist revolution of 2016 radically changed the trajectory of American politics. The 2008 financial collapse and the economic changes wrought by globalization had jolted the electorate, increasing the divide between coastal elites and America’s heartland. While the general election boiled down to a battle between Donald Trump and Hillary Clinton, the story of the future is about Trump and Bernie Sanders.

While Sanders, a self-described socialist, lost the 2016 primary to Clinton, his position atop an increasingly crowded field of announced 2020 Democratic hopefuls shows that he is winning the battle of ideas within the party.

Trump and Sanders espouse diametrically different policies, but share a strong populist appeal. Both shrug aside political norms in favor of politics that prioritize their version of what makes America great. Both are supported by a plurality of traditional party voters and are propelled by a populist wave. It would be a mistake to assume that because they have vastly different policy preferences there is no shared overlap in terms of their appeal — especially to heartland voters.

The national election map of the last 20 years (blue on the coasts, red in the middle) is so deeply ingrained that the thought of socialism rising in Middle America is, for many, unthinkable. Yet it is not far-fetched at all. In 2016, Sanders struggled on the elitist coasts but coasted in states like Wisconsin, where he beat Clinton 56 percent to 43 percent.

Sanders beat Clinton in solid red states such as Kansas, Idaho, and Indiana, as well as key Trump swing states such as Michigan and Wisconsin. Based on the 2016 primary map, it is clear that Sanders’ radical socialist vision for America was warmly received in the heartland.

This is not to say that the heartland is more socialist than New York or California. But it does suggest that America’s working-class voter needs hope, and the status quo isn’t cutting it. When it came to Clinton vs. Sanders, many Democrats in Middle America were ready to burn political norms to the ground, and Sanders held the matches.

Middle America is where the Trump-Sanders overlap is most pronounced. These voters, while not constituting a majority of Republicans or Democrats, were the key swing coalition in 2016 and will again play a key role in deciding the 2020 contest.

The fact that rural working-class voters swung to Trump over Clinton has been well reported. Less reported is that roughly 10 percent of Sanders’ Democratic primary voters voted for Trump in the general election. In Wisconsin and Michigan, the number of Sanders-Trump defectors is estimated to be about 48,000 and 51,000, respectively. Trump’s margins of victory in Wisconsin and Michigan were 22,748 and 10,704. In other words, Trump needed these Sanders voters to win.

This dynamic provides both a huge opportunity and major challenge for Republicans going into 2020. The opportunity is that voters can be convinced that Republican policies will make them better off. Adding this key constituency to the GOP base would build a durable governing coalition of working-class voters, suburban Republicans, and traditional conservatives. Such a coalition would be formidable in many elections to come.

The challenge is that the policies and ideas used to attract this new base must not abandon the free market principles that have fueled our nation’s economy. In short, the GOP must find a way to apply those principles to the specific challenges facing this crucial voting bloc.

2020 will be an opportune time for such a realignment, because Democrat candidates are aggressively moving left — Sens. Harris, Warren, Booker, Gillibrand and Klobuchar all co-sponsored Sanders’ Medicare-for-All platform and the Green New Deal resolution. Over the last two years, Sanders’ populist ideas have percolated throughout the Democratic Party, ensuring that no matter who wins the nomination, economic populism and borderline socialism will be the Democratic message.

This appeal to the working class has put their votes back in play for the Democratic Party in 2020. Conservatives must respond.

President Trump and Republicans in Congress fought to keep campaign promises by building the wall and lowering taxes. But this alone will not be enough to keep the 2016 coalition together.

The GOP needs to craft an agenda to keep working-class families on their side. It needs to be aspirational, positive, and relevant to the issues working families face on a daily basis. Without such an agenda, the allure of socialism can be incredibly real and enact long-term damage to our nation.