The AFL-CIO, the largest U.S. federation of labor unions, will launch digital attack ads targeting Republican front-runner Donald Trump next week as part of a multi-pronged effort to derail the New York billionaire’s bid for the White House and dampen union workers' enthusiasm for him. 

Officials at the AFL-CIO, an umbrella group of 56 unions representing 12.5 million workers, told Reuters the ads will depict Trump as anti-union, and will appear on Facebook and Twitter.

At the same time, an AFL-CIO affiliate organization will ramp up a door-to-door campaign to undermine the candidate in Ohio and Pennsylvania, key battleground states in the Nov. 8 presidential election.

"Donald Trump is nothing but a house of cards, and once we educate people, the house of cards comes crashing down," AFL-CIO president Richard Trumka told Reuters.

Union leaders are increasingly concerned about Trump’s appeal to labor, typically a stronghold of the Democratic Party, because of his promises to scrap free trade deals that have led to manufacturing job losses in the United States.