A very informative article from Counterpunch added depth and context to my understanding of The Poor People's Campaign The New Poor People's Campaign: Seeds Of A Non-Party Opposition?

Not settling for a choice between Democrats or Republicans:

There is a third strategic alternative: A “non-party opposition” which draws diverse constituencies out of their silos to combine their power but uses direct action rather than electoral politics as its means to exercise that power. Such a non-party opposition can play some of the crucial roles of a political party, bringing together different constituencies around common interests, exposing existing policies and institutions, and presenting alternatives.

The author covers the history and background of MLK's original PPC and then covers the organization that grew out of Rev. Barber's Moral Monday:

The testing ground for the new Poor People’s Campaign was what came to be known as the Forward Together movement that developed in North Carolina over the past dozen years. It shows how a coalition of movements, acting as a non-party opposition, can challenge reactionary political forces and transform the political arena.

The diverse, inclusive coalition:

Forward Together has become a coalition of 145 organizations representing Christians, Muslims, Jews, nonbelievers, blacks, Latinos, and poor whites, labor, civil rights, feminists and environmentalists, doctors and the uninsured, businesspeople and the unemployed, women and men, gay and straight, young and old, documented and undocumented. This unity was based on a belief that “none of us would be free until all of us were free.”

Solidarity manifested in “daily acts of justice and community building":

A number of principles have shaped Forward Together’s actions. One is simply “showing up to support any group in the state that was standing for justice.” In 2013 Forward Together supported the fight of Planned Parenthood and NARAL against new abortion restrictions. A few years later a hundred people filled a Durham church to demonstrate solidarity with a Durham-raised asylum seeker fighting deportation. Forward Together seeks “powerful images of solidarity” manifested in “daily acts of justice and community building.”

The new PPC is not a religious movement. I have run across a group in L.A. called Clergy and Laity United For Economic Justice that operates on the same idea:

But his is religion at its least sectarian: “It was often folk outside the church who inspired us the most, standing as examples of what the church should be,” he says; the church “didn’t have a monopoly on God’s dream.” And the goals of the movement were often expressed in secular political language: “Justice and community and the general welfare and the domestic tranquility and equal protection under the law” as guaranteed by state and federal constitutions. One journalist described the premise of the movement as a “universalist program” for health care, voting rights, reproductive choice, and higher wages that begins in “building coalitions among people whom politics have driven apart.”

(emphasis added)

The PPC is not Democratic or Republican:

Theoharis makes clear the political but non-party character of the campaign. “We surely want to influence the 2018 midterm elections and the 2020 Presidential election.” But they do not plan to endorse candidates or support any political party. Their statement of fundamental principles states that “no elected officials or candidates get the stage or serve on the State Organizing Committee of the Campaign.”

And:

Forward Together began making its demands for voting rights and equal justice when Democrats controlled the legislature and governorship and maintained that its agenda “wasn’t Republican or Democrat, liberal or conservative.” Unlike a political party or lobbying group, Forward Together has eschewed running or supporting candidates for office. Yet it has transformed North Carolina politics.

In conclusion:

The tens of millions of people who have participated in the Women’s March, the March for Our Lives, and the many other protests of the Trump era are marching in place in every community large or small. They have the potential to provide a vast grassroots network if the Poor People’s Campaign can reach out and inspire them to act together.

Conversely, all of us who have participated in one or another aspect of what has come to be known as the Trump Resistance should think about how we should be connecting with the new Poor People’s Campaign – and with each other. Perhaps we can make that campaign and similar efforts starting points for a non-party opposition that can challenge Trumpism and the power of the 1% — and indeed “transform the political, economic and moral structures of our society.”