The headline could have read "Canyons of the Ancients and Browns Canyon National Monument are reduced in size," but President Donald Trump instead moved his focus to Utah and signed two proclamations Monday, shrinking federally protected lands in the largest rollback of federally protected lands in history.

"The president knows and is going to see the negative reaction to this, and they're not going to want to do anymore of this. I think all of the Colorado National Monuments are safe," said Charles Wilkinson, University of Colorado law professor of Indian and Federal public land.

The Bears Ears National Monument will shrink to 220,000 acres from its current 1.5 million-acre size, and the Grand Staircase-Escalante National Monument will be cut in half to about 1 million acres, Interior Secretary Ryan Zinke said.

"The biggest users of the area are from Colorado," Wilkinson said. "What the president lacks is authority to take this action."

Trump's decision to roll back federal protections marks an unprecedented use of presidential power to shrink the national monument designations made by two of his predecessors.

"This is a radical act that the president has attempted to take. Either today or tomorrow, we will file a lawsuit in the District of Columbia," Wilkinson said.

Wilkinson is working with the Native American Rights Fund, a nonprofit Indian law firm that is already prepared try to reverse Monday's decision.

"Congress has ultimate authority over public lands and can delegate authority to the president, but Congress said in the future only Congress can change National Monuments, not presidents," Wilkinson said.

"It's one thing to say you have the power, it's another to test in a way that's not going to work. Either legally or politically this will not stand," said Troy Eid, former U.S. Attorney for Colorado.

Eid, a Republican, represented one of the Indian tribes that wanted Bears Ears protected and worked with former President Barack Obama when it was designated a national monument last year.

"If you were protecting the Sistine Chapel, would you just protect the altar or would you protect the whole church?" Eid said.

He said legal challenges could take years. In the meantime, vehicle traffic could increase, as well as oil and gas drilling, unless a challenge is made and a court issues an order preventing any activity.

Amy Roberts, executive director of Outdoor Industry Association, reiterated that this type of decision is why the Outdoor Retailer conventions are moving from Salt Lake City to Denver starting next month.