Within a week of its creation, the March for Science campaign had attracted more than 1.3 million supporters across Facebook and Twitter, cementing itself as a voice for people who are concerned about the future of science under President Trump.

Now, hoping to transform that viral success into something approaching the significance of the women’s march last month, the campaign has scheduled its demonstration in Washington for Earth Day, April 22.

“Yes, this is a protest, but it’s not a political protest,” said Jonathan Berman, a postdoctoral fellow at the University of Texas Health Science Center at San Antonio and a lead organizer of the march. “The people making decisions are in Washington, and they are the people we are trying to reach with the message: You should listen to evidence.”

Last week, Dr. Berman found himself in the middle of a social media movement. While browsing a Reddit discussion about how the new administration was handling science, he came across a comment that he interpreted as a call to arms: “There needs to be a Scientists’ March on Washington.”