Ahead of the nationwide “No Kings” protests against President Donald Trump’s administration, several civil rights and protest groups say they’re both eager to demonstrate widespread opposition to Trump’s agenda and concerned about potential retaliation.

Organizers predict the Oct. 18 rallies could become the “largest peaceful protest in modern American history,” according to Indivisible co-Executive Director Leah Greenberg.

Indivisible is among the groups supporting more than 2,500 rallies around the country. Others include the American Civil Liberties Union, the Freedom From Religion Foundation, the Human Rights Campaign and Planned Parenthood.

"This is the American people standing up and saying no, we're going to live in a democracy," said Deirdre Schifeling, the ACLU’s chief political and advocacy officer. "We don't have a king, we don't want a king, and we'll use our First Amendment rights to free speech to protest."

More than 5 million people participated in “No Kings” rallies in June, according to the ACLU.