Mary Kay Henry, president of the Service Employees International Union, and members of the Fight for $15 national organizing committee listen to Hillary Clinton on the phone. (Lydia DePillis/The Washington Post)

DETROIT, Mich. -- In one of the most explicitly union-friendly speeches of her young presidential campaign, Hillary Clinton called in to a convention of low-wage workers Sunday morning to deliver a message of support and solidarity.

"All of you should not have to march in the streets to get a living wage, but thank you for marching in the streets to get that living wage," she said. "We need you out there leading the fight against those who would rip away Americans’ right to organize, to collective bargaining, to fair pay."

Clinton's new campaign has carried a populist tone throughout, but this speech -- before a ballroom full of mostly young, African American workers from across the country -- virtually echoed the language that the Service Employees International Union has used in its campaign for a $15 minimum wage. Along with the fast food workers who have been at the core of scattered protests over the past couple of years, Clinton's short speech called out home care workers and adjunct professors, who make up a substantial part of the SEIU's membership base and have joined in the call for higher wages.

"No man or woman who works hard to feed America’s families should have to be on food stamps to feed your own families," Clinton said. "It is wrong that so many people stand against you thinking that they can steal your wages with no consequences. That even stacks the deck higher for those at the top."

The gathering in Detroit is the second of its kind, following a first convention last year. This time, the so-called "Fight for $15" has several victories to point to: $15 minimum wages in Seattle, San Francisco, and Los Angeles, plus new proposals for the same in St. Louis and Kansas City. New York Gov. Andrew Cuomo is even in the process of raising wages for fast food workers specifically in the state.

Clinton seemed to align herself with that campaign, to loud cheers from the audience.

"I want to be your champion. I want to fight with you every day," she said. "I’m well aware that the folks on top already have plenty of friends in Washington, but we together will change the direction of this great country."