In January, Reddit user Beaverteeth92 responded to a VICE article posted on Reddit — headlined “All References to Climate Change Have Been Deleted From the White House Website” — with a short comment: “There needs to be a Scientists’ March on Washington.”

It ballooned from there, and on Saturday people are expected to protest in over 600 cities, with tens of thousands of people expected at the main march in Washington, DC. It will likely be the largest demonstration in the capital since the Women’s March.

Its stated goals are to celebrate science and its contribution to society, while advocating for public partnerships and a more inclusive scientific community.

The march is officially nonpartisan, and organizers have stressed this repeatedly. But the motivations behind the march are clearly tied to the Trump administration’s war on science.

In his first days in office, President Donald Trump appointed a climate denier to the head of the EPA, has yet to nominate a science advisor (though the one he’s reportedly considering thinks climate change is actually a good thing), and banned the use of the term “climate change” in the energy department. He’s left the Office of Science and Innovation understaffed, and his budget calls for the elimination of hundreds of millions of dollars for scientific research. The same day he took office, the White House website was purged of any reference to climate change. He has also embraced entirely discredited theories that link vaccines to autism.

“People need to be aware that the quality of life and life expectancy they enjoy are largely due to scientific advances and the investment of the U.S. in the sciences,” Seun Ajiboye, a science policy analyst for the International and American Associations for Dental Research, told the New York Times.

But other scientists say they won’t attend. “It is a mistake to position the scientific method against the Trump administration or any other one, for that matter,” wrote Arthur W. Lambert on the science website, STAT. Those who are abstaining argue that mixing politics and science would tarnish the objectivity of their field.

Whatever the outcome of the march, it has prompted a debate within the scientific community about the role of science in the public sphere. Despite those actively sitting out the march, over 220 scientific organizations are supporting it, the New York Times reports. Other organizations, as disparate as the National Science Teachers’ Association and the United Automobile, Aerospace and Agricultural Implement Workers of America (UAW), are partnering with the march as well.