Millions are anticipated to march at more than 2,500 planned demonstrations against authoritarianism and militarization under Donald Trump.

Advocacy groups prepare for the "No Kings" rallies in the U.S., calling for government accountability and public vigilance under the Trump administration.

More than 2,500 protests against the administration are expected on Oct. 18. Organizers expect it to be the largest day of protest in U.S. history.