Ronald Reagan may have defined modern conservatism’s political tone, but Newt Gingrich was responsible for defining many of its policy terms. The GOP of two decades ago was the Party of Gingrich, one unified by national themes and ideological coherence and dedicated to “60 percent issues”—non-divisive policy items that had at least that support with voters. Over the past year, Donald Trump has run with the intention of razing that party and upending all of those Newtonian rules. He has jettisoned much of the party’s conservative policy orthodoxy, replacing it with populist nationalism, and has built his platform on some of the most divisive issues in American politics.

So it might seem surprising that the former speaker of the House of Representatives has become one of Trump’s most high-profile foot soldiers and is on the presumptive nominee’s shortlist for vice president. But the two men have far more in common than it would appear.

In the 1980s and ’90s, Gingrich developed an obsessive focus on messaging, cultivating a political vernacular aimed at exploiting and stoking mistrust of Washington. This disruptive and symbolic politics of nihilism are now hallmarks of the Trump campaign. Gingrich also urged his fellow Republican representatives to transition from focusing on local issues to national ones, a shift that fostered much of the alienation on which Trump now feeds. In short, Gingrich wrote the slash-and-burn playbook that Trump has employed over the past year, and Gingrich’s Republican revolution created the conditions and political mood that allowed Trump to succeed.

Even before his election to Congress, Professor Gingrich kept a file on “Populism” in his office at West Georgia College that contained news clippings describing Americans’ loss of faith in government (one headline: “Why People Are Mad at Washington”). In 1979, he entered the House with a plan to forge a new generation of conservative leadership. But while he presented himself as a devout conservative, he built a platform around more pragmatic concerns. With poll-driven priorities, his Conservative Opportunity Society—a group of young, right-wing representatives intent on advancing a conservative agenda in the House—was as much about opportunism as opportunity.

Like Trump, Gingrich reveled in crossing symbolic partisan lines to signal his pragmatic reasonableness. He compared his tax policies to those of John F. Kennedy. He defended the Conservative Opportunity Society by equating it with the New Deal (“we believe in the New Deal,” he pledged in 1982. Like Trump exploiting the unmet needs of the GOP’s white working class, in the early 1980s Gingrich spotted holes in the political landscape and offered policies to fill them, supporting tech-industry investments, health insurance reforms, and tax simplification over tax cuts. This made him a rare political creature: the undogmatic ideologue.