President Donald Trump will travel to Utah on Monday to lay out his plans to cut the size of Bears Ears and Grand Staircase-Escalante National Monuments, according to individuals briefed on the matter who spoke on the condition of anonymity because it had not been formally announced.

Democratic presidents established the two national monuments in southern Utah under the 1906 Antiquities Act, and both of them have generated considerable controversy. Barack Obama established Bears Ears, a 1.35-million-acre expanse that is home to tens of thousands of ancestral Pueblo archaeological sites, nearly a year ago, while Bill Clinton designated the nearly 1.9-million-acre Grand Staircase-Escalante in 1996.

Interior Secretary Ryan Zinke recommended scaling back both monuments, along with several others, as part of a report he delivered to the White House in August. Since that time, White House officials have been working with staff at Interior and the Justice department to draft proclamations that they think have the best chance of withstanding an inevitable court challenge from conservation and tribal groups, according to a senior administration official.

Neither the White House nor Interior immediately responded to a request for comment Tuesday.

While administration officials have not announced how much Trump plans to reduce either monument, they have privately indicated he intends to shave hundreds of thousands of acres off both.

The president will reduce Bears Ears by more than 1 million acres, Interior officials have informed multiple individuals who spoke on the condition of anonymity because they were not authorized to speak on the record. And Ron Dean, an aide to Sen. Orrin Hatch, R-Utah, testified before the Utah Legislature’s Commission for the Stewardship of Public Lands this month that “Grand Staircase will probably be somewhere between 700,000 acres and 1.2 million” under the revised designation.

State and local officials, nearly all of whom are Republicans, fought the designation of Bears Ears as a national monument and lobbied the Trump administration to either rescind it altogether or scale it back significantly.

“We’re extremely grateful for the president’s visit, and the [Interior] Secretary’s work that led up to this visit,” said San Juan County Commissioner Phil Lyman, R, in an interview Tuesday. “We feel like we’ve been listened to, and that means a lot to us.”

Trump does not intend to visit the monuments themselves, individuals briefed on the plans said, but will instead travel to Salt Lake City.

Environmentalists quickly decried the move to shrink the monuments, and vowed to block it through litigation.

“This illegal action will cement Trump’s legacy as one of the worst presidents in modern history,” said Randi Spivak, public lands program director at the advocacy group Center for Biological Diversity. “Trump has no clue how much people love these sacred and irreplaceable landscapes, but he’s about to find out. He’s shown his blatant disregard for public lands, Native Americans and the law. We look forward to seeing him in court.”

The administration is in the process of drafting other proclamations under the Antiquities Act that would alter the size of some national monuments and change the way others are managed. Those proclamations will be issued over a period of several weeks following the Utah trip, a senior administration official said.

San Juan County Commission Chairman Bruce Adams said in an interview Tuesday that changing the size of Bears Ears was only “half the race,” because he and others want Congress to limit the president’s authority to designate protections on federal land under the Antiquities Act.

Adams noted that more than half of the county’s land is federally owned and another quarter is made up of Navajo reservation land, thereby restraining local officials’ ability to raise money through private property taxes.

“We don’t want to have to go down this road every four years, in San Juan County or in the state of Utah,” Adams said. “We’re challenged with providing services for five million acres, whether we get revenue from those five million acres or not.”