Most pastors say they preach the truth. The Rev. William Barber also delivers sermons on another topic: "the trick."

The trick is Barber's term for something that he describes as a weapon of mass distraction. It stymied the leaders of the populist movement in late 19th century. It vexed union leaders who promoted workers' solidarity. The Rev. Martin Luther King Jr. King died trying to beat the trick.

The trick is when white politicians persuade poor white working class people that the source of their pain is people of color, immigrants and other scapegoats, says Barber, who rose to national fame after helping lead Moral Mondays, a social justice movement formed in North Carolina.

"You have to show them the trick," says Barber, his rich, baritone shifting into preaching mode when asked how he would address this challenge.

"The majority of people in this country who are poor are white people. You have to undermine the trick and say, 'Listen, you want a living wage, but the people you voted for don't want a living wage. You're upset that you don't have health care. Guess what, black and Latino people aren't your problems. It's the people who are voting against health care.' "

Barber's message worked in North Carolina, and now he and others are taking it nationally on Monday to revive King's boldest crusade: the Poor People's Campaign.

Organizers for a "new Poor People's Campaign" and the Fight for $15 movement say they will launch rallies across the mid-South to raise awareness of the plight of the nation's poor.

The campaign is calling for thousands of cooks and cashiers to walk off their jobs Monday and join protests in two dozen cities. A march is planned in Memphis, Tennessee, retracing the route King took during his fateful last campaign. And six weeks of "direct action and nonviolent civil disobedience" are planned starting May 13, Mother's Day.

Behind the flurry of events, this new campaign could provide an answer to a question that has long tantalized historians and activists: What if King had lived to see his Poor People's Campaign through. Could it have worked?

It was certainly daring enough. King and his staff were mobilizing an interracial army to occupy Washington much like Occupy Wall Street set up camp in New York's financial district in 2011. He had recruited impoverished white residents of Appalachia, Latino farm workers from California and impoverished blacks from Mississippi. It was a Rainbow Coalition before the term was even coined.

The campaign disintegrated, though, after King was assassinated in Memphis on April 4, 1968, while supporting a strike of black sanitation workers. The new Poor People's Campaign will follow part of the blueprint of King's old campaign, Barber says: build a movement across racial lines and across an array of issues.

Call the new poor people's movement a civil rights campaign, though, and Barber immediately pounces.

"That language is too puny -- it's designed to divide," he says. "We didn't build a white movement or a black movement [in North Carolina]. We built a moral movement."

The new campaign is supported by one of the nation's largest unions, the Service Employees International Union. The union has provided much of the organizational muscle and money behind the Fight for $15 campaign, which has helped organize fast-food workers across the nation and persuaded many states and cities to raise their minimum wage.

Mary Kay Henry, the international president of the SEIU, says her union has committed to the new Poor People's Campaign beyond this year. She is already talking about how it could help mobilize voters for the 2020 presidential election.

Henry also alluded to "the trick." Some say unions do a better job of inoculating white members from racist appeals because they promote relationships among people of different races. Henry evoked this tradition.

"White working people, when they are in relationship in union organizations, understand that we all have to join together to lift things up," she says.

Even if King survived, some historians say the original Poor People's Campaign would have floundered because the nation had turned away from King and the poor by 1968. The terrain in Washington may be more difficult this time, with inequality even worse now than when King was alive.

Barber, though, doesn't sound daunted. Social justice movements rarely start out as popular campaigns, he says. When the abolitionist movement first mobilized against slavery, the slave-holding states in America held sway in Washington. When King marched for voting rights in 1965, Congress and the President didn't want to act on the issue, he says.

"If people in the civil rights movement had waited until people were with them," Barber says, "they would have waited forever."