Like Trump, much of Brown’s populist message is deeply rooted in the economic anxieties felt by Americans — though he’s been at it considerably longer than the president.

First elected to the state House in 1974, Brown didn’t follow the conventional path of most young, ambitious politicians. Rather than spend time in the capital of Columbus making a name for himself and wooing donors and party leaders, Brown would return home each week to Mansfield, where he’d spend long days in the local steelworkers union hall. Over cups of coffee, the white-collar son of a doctor listened to the union members as they talked about their economic worries.

With the country plunging into its first recession since World War II, there was plenty of economic anxiety to go around in the '70s. Gas prices were high, factories were closing, and the job market was grim.

Those stories, according to Brown, played a key role in his adoption of a populist viewpoint. “To me, real populism is embracing the little guy, regardless of what the little guy is,” Brown says.

That has been the core of his politics since, even when it’s been unpopular with the powers that be in the Democratic Party. In 1993 as a freshman member of Congress, he clashed with the Clinton administration over the North American Free Trade Agreement, becoming one of the leaders of the opposition to the deal. Although they lost, Brown continued to fight massive trade agreements during the Bush and Obama years, and last year he was a key figure in helping bring down the Trans Pacific Partnership, one of Obama’s top priorities in the waning months of his presidency.

John Ryan, Brown’s state director for the last 10 years, says he was initially skeptical of Brown, but over time it became clear that Brown had taken the stories of Mansfield’s workers to heart. “He had my politics, this working class politics … even though he was raised, not wealthy, but certainly comfortable. It tells you something about his commitment to community and to people,” Ryan explained.

Even more surprising, he noted, has been his dedication to his populist views. “Most politicians just get worn down,” Ryan said, laughing.

Brown grew up with progressive parents —at 17, they took him to an anti-war protest in Washington— who practiced the same social justice–focused Lutheranism he still embraces today.

His voting record in Congress is one of the most liberal on social issues: He was one of only two Ohio members of Congress to vote against the Defense of Marriage Act in 1996, he opposed the 2002 Iraq War resolution, he has been a vocal supporter of Obamacare, and he was the first senator to come out against the nomination of Jeff Sessions to become attorney general.