Major star power is behind the upcoming Women's March on Washington (WMW).

Organizers expect tens of thousands of people to attend the rally Jan. 21 in D.C. near the U.S. Capitol, which aims to send a message to "all levels of government" about defending equality and human rights.

Katy Perry, Cher, Scarlett Johansson expected

Comedian Amy Schumer, pop star Katy Perry, Cher and Ugly Betty's America Ferrera are among the Hollywood celebrities planning to attend.

"Since the election, so many fear that their voices will go unheard," Ferrera, who will serve as chair of the Artist Table, said in a statement earlier this week. "As artists, women, and most importantly dedicated Americans, it is critical that we stand together in solidarity for the protection, dignity, and rights of our communities.

The march will take place one day after president-elect Donald Trump's inauguration, although organizers say the planned demonstration is not specifically anti-Trump.

ferrera-america-getty-cp-103873891

Actress America Ferrera will chair the WMW's Artist Table. ((Francois Durand/Getty Images))

Fighting to protect 'bodies' and 'choices'

Comedian Chelsea Handler, Patricia Arquette, Oliva Wilde, Julianne Moore, Orange is the New Black's Uzo Aduba, and The Avengers actress Scarlett Johansson are also scheduled to participate.

"I am marching on Washington to let our next president know that we, men and women alike, will not stand down or be silenced and will fight to protect our bodies and our choices," Johansson said in a statement, referring to the Trump administration's plans to de-fund Planned Parenthood.

FILM FESTIVAL-TIFF Scarlett Johansson 2016

Actress Scarlett Johansson is among the Hollywood actors expected to attend the march. (Reuters)

Standing in solidarity

Singer-actress Zendaya, Will & Grace star Debra Messing and actress Rosie Perez are also getting involved in the event, which is hosting more than 300 "sister" marches across the U.S., Canada and around the world.

2015 Billboard Music Awards - Arrivals

Zendaya, seen here at the 2015 Billboard Music Awards and known for her work with the Disney channel, is among those joining Saturday's march. (Eric Jamison/Invision/AP)

"We stand together in solidarity and we expect elected leaders to act to protect the rights of women, their families and their communities," the WMW organization wrote in a statement on its website.