LOS ANGELES >> At a rally Tuesday, four local members of Congress blasted President Trump’s executive order that called for the review of dozens of national monuments, which they fear could mean scaling back or eliminating those protected natural areas entirely.

Among the 21 monuments under review are the San Gabriel Mountains, which President Obama dedicated in 2014.

During his time in the White House, Obama dedicated 34 national monuments under the 1906 Antiquities Act, more than any other president.

But in April, Trump said the federal government should not have “unlimited power to lock up millions of acres of land and water,” and ordered the Interior Department to review any monument over 100,000 acres.

The representatives on Tuesday — Judy Chu of Pasadena, Jimmy Gomez of Los Angeles, Brad Sherman of Sherman Oaks and Adam Schiff of Burbank, all Democrats — condemned Trump’s decision to review the monuments, saying the president’s action was a nod to corporate greed.

They claimed the process was part of secret dealings between the administration and oil, gas and mining firms seeking permission to recover additional resources from federal lands marked for preservation by previous presidents.

The sharp remarks against Trump’s environmental record and the reviews, which in addition to the San Gabriel Mountains will look California’s Giant Sequoias and the Mojave Trails national monuments, come just two days before Interior Secretary Ryan Zinke is scheduled to release his report.

• Photos: Local politicians rally for monuments

Speaking to a friendly crowd of about 100 supporters at the Los Angeles Historic Park near Chinatown, the local representatives spoke in blunt terms, even threatening to block an attempt at monument trimming with legal action.

“There is a lot we don’t know about this latest assault on the environment bought to us by the same administration that abandoned the global effort to fight climate change,” said Schiff, who has become an outspoken critic of the Trump Administration and its policies.

Schiff referred to President Trump’s decision to back out of the Paris climate change agreement in June, as well as to Environmental Protection Agency Administrator Scott Pruitt’s moves to undo or delay 30 environmental rules for curbing pollution, protecting the nation’s waterways and allowing greater use of once-banned pesticides.

“I think we don’t want to establish a precedent where a president without approval of Congress can simply eviscerate a national monument,” Schiff said.

The White House has already said some monuments are no longer on the chopping block. Zinke pointed out several that would not be changed: the Grand Canyon-Parashant, Sand to Snow in San Bernardino County northern Riverside County, Canyons of the Ancients in Colorado, Craters of the Moon in Idaho, Upper Missouri River Breaks in Montana and Hanford Reach in Washington.

Chu said Trump and Zinke want to allow oil and gas exploration in the Bears Ears, 1.35 million acres of sacred tribal lands designated by Obama last year. There’s no case for digging for oil in the San Gabriel Mountains, Chu said.

“In our case, there is not an economic interest that prevents it from going forward. There is no mining. Not at all,” she said.

Schiff claimed Trump’s motives were simply to erase Obama’s legacy.

“Like so many other actions, this current president would tear down what others have done, offering nothing constructive in its place,” Schiff told the crowd. “We will resist.”

Rep. Paul Cook, R-San Bernardino, sent a letter to Zinke, asking him to remove a 4,873-acre finger of the San Gabriels monument that juts into the San Bernardino National Forest. The overwhelming majority of the 346,177-acre monument is in the Angeles National Forest, including craggy peaks and dark canyons from Santa Clarita to the Sheep Mountain Wilderness and the Bridge to Nowhere in San Gabriel Canyon.

Cook said the process did not include outreach to communities and leaders from San Bernardino County.

“That is another one of President Trump’s distortions. It is time for some truth,” Chu told the crowd.

Chu, of Pasadena, said the effort started 10 years before the designation by Obama on Oct. 10, 2014, and included 66 stakeholder meetings and 16,800 comments with 80 percent in favor. She praised a 46-member monument collaborative consisting of members from business, conservation, recreation, cities and utilities for working with the U.S. Forest Service on improving the monument’s trails, picnic and recreation areas. The group unanimously agreed to ask Zinke to leave the monument’s boundaries as is.

People in the crowd waved signs that said “Keep your tiny hands off our public lands” and one supporter drew a sign with Smokey the Bear and the word “Resist.”

When asked if losing a tiny portion of the monument would be detrimental, Schiff said it depends if those in San Bernardino County would damage the environment or open it to development.

“If this were something in isolation, you could make a policy argument. But of course, it is not. It is part of a comprehensive attack on nature and the environment,” Schiff said.