Brown’s catchphrase is catching on. It’s popped out of the mouths of other Democrats running for president and their surrogates in recent weeks.Rep. Lori Trahan used it at Sen. Elizabeth Warren’s presidential launch in Lawrence, Massachusetts, earlier this month. Democratic contenders Sen. Kamala Harris and Sen. Cory Booker employed it themselves. Even the anti-union billionaire Howard Schultz used the phrase while speaking to students at Purdue University a few weeks ago.

Brown believes it’s exactly because of his progressive policies that he won, not in spite of them, and he’s long pushed pro-worker policies in the Senate, such as making expanded worker tax credits a permanent part of the tax code.

Brown has made a career out of winning over Ohio workers with an atypical progressive message. Just two years after President Donald Trump won the critical swing state by 8 percentage points, Brown easily held onto his Senate seat last year, even with a policy platform that would raise the federal minimum wage to $15 per hour, expand tax credits and make it easier for workers to form unions.

“The dignity of work means hard work should pay off for everyone, no matter who you are or what kind of work you do,” he told a crowd in Brunswick, Ohio.

It’s not a new phrase. Martin Luther King Jr. invoked it in defense of striking workers in Memphis, Tennessee, in 1968. So have Republicans while kicking people off welfare. Now, as he weighs a possible presidential run, the Ohio Democrat is making it his own, using it as the title of the national listening tour he launched last month.

Sen. Sherrod Brown is testing the waters of the 2020 Democratic primary with a slogan designed to win over increasingly anxious blue collar workers: “the dignity of work.”

Brown isn’t bothered by his fellow Democrats using the phrase. He told HuffPost that when he first considered doing a listening tour last year, his goal was to “inform the Democratic debates” and “get people thinking more about workers.”

Brown took inspiration from scripture, and especially from King, who said in March 1968 that America’s salvation depended on paying properly for “the dignity of labor.”

“If America does not use her vast resources of wealth to end poverty and make it possible for all of God’s children to have the basic necessities of life, she, too, will go to hell,” King told striking sanitation workers in Memphis, Tennessee, just weeks before his assassination.

But between 1968 and today, the phrase has taken some political twists and turns, as Republicans have used it to push an agenda that undermines workers at almost every turn.

Sen. Marco Rubio, for one, wrote in a December op-ed that corporate tax cuts promote the dignity of work and that American worker unions do not. That same month, the Trump administration said that a proposed regulation that would kick hundreds of thousands of people off food stamps “restores the dignity of work to a sizeable segment of our population, while it is also respectful of the taxpayers who fund the program.”

“Republicans are far too accepting of low-wage jobs,” said Brown, who feuded with Rubio on Twitter over the slogan. “I hear Rubio say that, I hear Trump say that ― I think it’s a justification for their anti-union policy.”

During the welfare reform debate of the mid-1990s, Republicans mentioned the “dignity of work” dozens of times in floor debate. With President Bill Clinton’s help, they all but eradicated cash welfare for poor single mothers, resulting in a surge of dignity as well as a stark increase in extreme cashless poverty.

Republicans have sought to replicate the supposed success of welfare reform at every opportunity. The GOP’s domestic policy agenda consistently seeks to undercut workers ― whether by making food stamps less generous, weakening the overtime protections in the Fair Labor Standards Act, or reducing access to health care outside of employment.

Such policies make it more difficult to survive without market income, meaning workers become more desperate for whatever job is available at whatever pay is offered. The desperation benefits employers, but in the Republican view, it also benefits workers, because even underpaid work confers the nonmonetary benefit of “dignity.” That’s why former House Speaker Paul Ryan (R) used to say that just alleviating material hardship directly might give someone a “full stomach and an empty soul.”

But labor advocates also have a long history of emphasizing work’s dignity. Pope John Paul II promoted “the dignity of work” in a 1981 encyclical that said working is a fundamental part of being human, and that work is good so long as it’s not exploitive. The U.S. Conference of Catholic Bishops, which lobbies in favor of liberal economic policies, will tell you all about where you can find pro-worker passages in the Bible.

“[‘The dignity of work’] has been used over time for different purposes,” said Sharon Parrott, a senior fellow at the liberal Center on Budget and Policy Priorities. “Sometimes it’s used to denigrate people who are out of work, sometimes it’s used to express a broadly shared American value ― that people want to work.”

The correct understanding of the concept, Parrott said, is that when someone isn’t fairly compensated by the private sector for their work effort, the government should protect the dignity of work by making sure that worker’s basic needs are met. That means ensuring adequate access to food, shelter and medical care.

The danger of the term, said Elizabeth Lower-Basch of the liberal Center for Law and Social Policy, is “when you assume that what people do for a paycheck has worth and what they do for other reasons does not.” Lower-Basch said she was confident Brown used the term the right way; he has stressed that dignity extends to work inside the home, such as caring for a child or an aging parent.

Brown believes the appeal of such a phrase is “universal,” transcending the geographic and political divides of the country. “Because we are a society that undervalues work,” he said.

“To me, it’s not a slogan. It’s the way you govern, and it’s who I am,” Brown said. “Whether I run for president or not, we will continue to use that term.”