The Ohio Democrat launched his "dignity of work" tour at a warehouse south of Cleveland. He and his wife, journalist Connie Schultz, head next to Iowa, New Hampshire, Nevada and South Carolina.
The 66-year-old senator and former representative told the crowd of several hundred that Democrats can't let "extremists" at statehouses and in Washington claim populist credentials if they don't support policies that benefit middle-class Americans.
Steve Norris, 38, a software developer from Lakewood, said he would love to see better benefits and wages for workers his age, something Brown said he would fight for.
"You talk to some of the older people, and it would be great to get some of the deals they had," he said.
Christopher Mobley, 18, said the College Democrats at the University of Akron, of which he's a part, are excited to support Brown "because he's someone that's not going to take anything from Trump."
"Donald Trump has used his phony populism to divide Americans and to demonize immigrants. He uses phony populism to distract from the fact that he's used the White House to enrich billionaires like himself," Brown said. "Because real populism is not racist; real populism is not anti-Semitic; real populists don't engage in hate speech and don't rip babies from families at the border."
The fight for the populist label is no small thing to Brown, who will argue in the four other states that his decisive re-election in November showed the power a progressive message can have in a state that Trump won by double digits. Supporters at the event recalled fighting for workers and families for decades.
"Sherrod is the one candidate who's like an old-school Democrat, that hasn't forgotten where the Democratic Party started," said Teamster Fred Crow, 57, of Maple Heights. "Sherrod's the one guy that's been with us from the beginning."
Many working-class supporters in attendance said they felt betrayed or duped by Trump, who won Ohio decisively in 2016 with the support of many blue-collar workers who switched parties to give him their vote.
"He hornswoggled us," said Albert Stapleton, 73, a retired Teamster and 2016 Trump voter from Brunswick. "He went 180 (degrees) out on everything that he campaigned on."
Crow said: "Mr. Trump is the drunk at the end of the bar. He's going to tell you what you want to hear."
Rather than disappearing after the rally, Brown and Schultz remained for nearly an hour mingling and taking photos with backers.