Donald Trump has reached the brink of the Republican presidential nomination in part by selling himself as the solution to the working-class blues, but the nation's top union official plans to tell a labor conference in Atlantic City Tuesday that it's all a lie.

"Donald Trump talks a big game about making America great. He says he's a friend of workers," AFL-CIO President Richard Trumka will say, according to excerpts of his speech to the organization's New Jersey state convention. "But Trump doesn't have our backs -- he wants to break our backs."

Trumka will discuss Trump's record of labor violations, outsourcing the manufacture of some of his branded products and the now defunct for-profit Trump University, subject of fraud lawsuits charging it was a scam aimed at the vulnerable.

The leader of the 12.5-million-member AFL-CIO is making his first appearance since the organization endorsed Democrat Hillary Clinton last week. His message could find a special resonance in Atlantic City where, over the years, Trump has left a trail of unpaid and underpaid bills in the wake of several bankrupt casinos.

"It's our job to explain that Donald Trump won't solve America's problems. He is the problem," Trumka plans to say. "Name any core American value, and Donald Trump is against it: Freedom of religion. Freedom of the press.  Responsibility. Equality.Unity. Integrity. He stands against everything we stand for."

He is speaking the same day Clinton plans to argue in a major speech in Columbus, Ohio that Trump would be a disaster as steward of the U.S. economy. He has pledged massive tax cuts for the wealthy and tariffs on trade with China and Mexico that could trigger a recession, said Jake Sullivan, senior adviser to Clinton. Trump "would very likely drive us off a cliff," Sullivan said.

The convention occurs just after a victory for the union movement, a new contract with Verizon that will limit the company's planned outsourcing of call-center jobs. And it also comes as union members at five of Atlantic City's remaining casinos have authorized a July 1 strike over wage and benefit freezes.

AFL-CIO remained neutral during the primary contest between Clinton and Vermont Sen. Bernie Sanders, the fiery democratic socialist, though some member unions backed one or the other. Trumka said in an interview Monday that there was a "groundswell" among rank-and-file union members that it was time to rally behind Clinton, who has won the support of enough national convention delegates to secure the nomination.

"I think we had two quality candidates running, both of which supported working people," Trumka said. He said that Clinton is the most qualified presidential candidate in his lifetime, and praised her opposition to the pending Trans Pacific Partnership free-trade agreement.

AFL-CIO will mount "the most sophisticated target program in our history," Trumka said – communicating with union members and working-class voters at worksites, through the mail and on the phone, to build support for Democrats.

"There's a chance for us to rewrite the rules (of the economy), and we've been waiting for that chance for decades," Trumka said. "We're not going to let it pass us by."