The nation's largest union is throwing its weight behind the anti-Trump Women's March.

AFL-CIO announced that it will participate in Wednesday's A Day Without A Woman protest, in which women are encouraged to abstain from working or performing domestic duties. The 13-million-member union plans to march to the Labor Department, saying it will focus on sexual harassment and working conditions for women, according to a letter penned by AFL-CIO organizer Sheva Diagne.

"Working women from multiple sectors will rally and surround the Department of Labor in a show of unity, demanding that women workers be seen, heard, and treated with dignity, especially by the new Presidential Administration and Department of Labor leadership," the union said in a letter.

President Donald Trump has been unsuccessful at staffing the Labor Department after his first nominee, fast food executive Andy Puzder, withdrew in February. Labor groups waged a fierce campaign against Puzder, who would have been the first career businessman to serve as labor secretary since 1985.

Following Puzder's withdrawal, Trump tapped Alexander Acosta, the dean of Florida International University's law school and a former National Labor Relations Board member, for the post. Several unions have endorsed Acosta and AFL-CIO President Richard Trumka praised his record, saying he deserves "serious consideration."

Women make up 48 percent of all union members in the country, according to the Bureau of Labor Statistics. Union membership, however, has fallen to record lows over the past thirty years. Less than 11 percent of workers belong to unions, down from about 15 percent in 2000.

Unions have downsized as a result of shrinking membership and dues collections. The AFL-CIO laid off dozens of workers in its Washington, D.C., headquarters even after increasing revenue from $182.4 million in 2015 to $188.7 million in 2016. A spokesman told Bloomberg News that the headquarter staff would be reduced in order to focus more on "core priorities."

"We will have to end support for some programs that don’t go to our core priorities," the spokesman said. "This is about reimagining and realigning our core priorities to best serve our affiliates."

Those "core priorities" appear to include anti-Trump protests. AFL-CIO organizers encouraged rally attendees to share their stories about harassment in the workplace. The rally will bring in artists to organize "a flash mob, poetry, music, and much more." Diagne said artistic expression is crucial to raise awareness about working conditions in the United States.

"Through an artistic uprising, collective expression and creative resistance, women workers and artists will share personal powerful moving testimonies experienced on the job," the letter said.

AFL-CIO found that Trump enjoyed more support from union members than past Republican nominees. Hillary Clinton won union voters 56-37, according to an exit poll obtained by the New York Times' Noam Scheiber and MSNBC's Alex Seitz-Wald. That was a 12 percent improvement from 2012, when Obama won union voters 65-33.

The Wednesday protest is scheduled to begin at 3:30 p.m. outside the Labor Department's D.C. headquarters on Constitution Ave.

Update March 10 10:08 a.m.: The AFL-CIO's exit poll of union members was not conducted by AFL-CIO affiliate Working America, as an earlier version of this story first reported. Working America conducted a separate report surveying working-class neighborhoods in five battleground states; that report also found Clinton with a 56-37 advantage.