SALT LAKE CITY — Conservation and tribal groups are airing TV ads, sending letters to President Trump and creating parody websites in a last-minute blitz to stop Interior Secretary Ryan Zinke from downsizing or eliminating national monument areas that cover large swaths of land and water from Maine to California.

The deadline for Zinke to announce his recommendations is Thursday following a four-month review of 27 sites ordered by Trump.

A tribal coalition that pushed for the Bears Ears National Monument in Utah, designated by President Barack Obama in December, unveiled a new webpage Tuesday that explains the cultural importance of lands consider sacred to them. They also posted a letter sent to Trump telling him that part of “making American great again” is honoring tribal history and rights.

“At a time when the United States feels anything but united under the shadow of Charlottesville, Virginia, please hear our voices,” wrote Willie Grayeyes, chairman of the coalition. “These sacred lands have held our song, our stories, and our prayers since time beyond memory, and these lands will continue to hold the promise of our future.”

The outdoor recreation industry has hammered home its message that peeling back protections on areas where its customers hike, bike and camp could prevent future generations from enjoying the sites.

In addition, the Wilderness Society has created a parody website featuring Trump and Zinke selling luxury real estate at the sites.

Groups that want to see the areas reduced have been less vociferous, pleading their cases on social media and working behind the scenes to lobby federal officials.

They say past presidents have misused a century-old law to create monuments that are too large and stop drilling, grazing, mining and other uses.

Stan Summers, a Utah county commissioner, said outdoor recreation companies are peddling lies and misconceptions when they say local officials want to bulldoze monument lands.

Summers said residents treasure the lands that comprise Bears Ears and the Grand Staircase-Escalante monuments in Utah, but don’t want to close the areas to new oil drilling and mining that produce good jobs.

“We want to tend this area like a garden instead of a museum,” he said

The review includes sweeping sites mostly in the West that are home to ancient cliff dwellings, towering sequoia trees, deep canyons or ocean habitats roamed by seals, whales and sea turtles.

Zinke has already removed six areas in Montana, Colorado, Idaho and Washington from consideration for changes. He also said Bears Ears on tribal land in Utah should be downsized.

Environmental groups said the 1906 Antiquities Act is intended to shield significant historical and archaeological sites, and that it allows presidents to create the monuments but only gives Congress the power to modify them.

No other president has tried to eliminate a monument, but they have trimmed and redrawn boundaries 18 times, according to the National Park Service.