President Trump is expected to sign an executive order Wednesday that could end up shrinking — or even nullifying — some large federal national monuments on protected public lands, as established since the Clinton administration.

The move is largely seen as a response by the new administration to two controversial, sweeping national monument designations made late in the Obama administration: the new Bears Ears National Monument in Utah considered sacred to Native American tribes and the Gold Butte National Monument in Nevada near the Bundy Ranch, site of the 2014 armed standoff over cattle grazing on public land.

In a briefing with reporters at the White House Tuesday night, Interior Secretary Ryan Zinke said the order will direct his department to review all national monument designations on federal public land since 1996 that are 100,000 acres or more in size. The secretary didn't say whether he would recommend that Bears Ears be shrunk or abolished, only that a review of the designations was long overdue.

"The executive order does not strip any monument of a designation," Zinke said. "The executive order does not loosen any environmental or conservation regulation on any land or marine areas."

Zinke added that he expected the review to look at the boundaries of these monuments and whether sacred sites like cliff dwellings or other important national treasures, as he put it, could still be protected if the monuments were smaller.

Republican and Democratic presidents including George W. Bush and Barack Obama have used the 1906 Antiquities Act to protect large swaths of federal public lands, mostly in the West. Under the Act, only Congress, not the president, has the clear authority to reduce or nullify a monument designation. If the Trump Administration presses forward on its own, it's widely thought the matter will swiftly land in court.

"It's untested," Zinke noted Tuesday.

Designations like the recent Bears Ears often protect large amounts of public land, while grandfathering in certain historical uses like existing cattle grazing leases and mining claims. But new development is largely restricted, which is the source of heated controversy in rural towns surrounded by federal land where many residents make their living from natural resources.

On the other hand, sportsmen groups, conservationists and tribes in some of these same rural areas point to big job gains and tourist revenue where federal land get protection.

Many of these groups aren't mincing words either over the president's expected order tomorrow.

Shawn Chapoose, chairman of the Ute Tribe in Fort Duchesne, Utah, called it an attack on Indian Country.

"Once you destroy these types of resources, these habitats, these areas that are untouched, you can never go back," he said.

Under the order, the Interior Department is expected to review up to 40 monuments, dating back to the Grand Staircase Escalante National Monument in Utah, first protected by the Clinton administration. Trump has ordered a preliminary report from the agency within 45 days.

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