Major environmental groups are guarding against a potential order from President Donald Trump that could strip away their tax-exempt status, sources familiar with the matter told Bloomberg Law Wednesday.

Multiple environmental and conservation organizations are discussing preparations and assembling legal teams in response to the speculation, according to sources who agreed to speak on the condition of anonymity.

“This is going to be focused on climate activism, not environmentalism in general,” according to Kieran Suckling, executive director for the Center for Biological Diversity.

Some say the order—which could also seize funds and designate groups as domestic terrorists—will be released on Earth Day, April 22.

Suckling confirmed the Center is also actively preparing for a potential order, and vows to sue for a temporary restraining order if it comes down. It is unclear whether such an order would survive legal scrutiny.

The White House didn’t immediately respond to a request for comment.

A federal judge on Tuesday ordered the federal government to unfreeze billions in climate and infrastructure funds, which Trump froze via executive order on his first day in office.