Worried union leaders say many members feel "outshouted" by powerful political voices and are showing anger by backing extreme candidates.
Clinton's passion for workers' causes, from project labor agreements to being their advocate in the White House, excited the audience.
"It's time to win Washington State and the rest of the West for Bernie Sanders!'
AFL-CIO President Richard Trumka challenged Donald Trump's appeal to working class voters.
"Without a countervailing pull of authentic engagement, the appeal of right wing rhetoric will continue."
Participants in the Republican caucuses ignored Trump's violation of worker rights and gave him a double-digit victory.
"Secretary Clinton has proven herself as a fighter and champion working people and their families need in the White House."
However, major unions that are part of the federation have already endorsed Clinton while others have come out for Sanders.
Like a preacher of prejudice, Trump validates cursing the nation's marginalized and accusing them of emptying workers' bank accounts.
Have Donald Trump's promises played like the sound of music to the ears of American workers?