A little-known federal historic preservation agency said Thursday it’s giving up on trying to get Virginia and Washington, D.C., on board behind plans for President Donald Trump’s triumphal arch and indicates the administration will move forward with the project anyway.

The Advisory Council for Historic Preservation (ACHP) wrote in a letter to the National Park Service that it is “terminating” required consultation with local officials about ways to minimize the adverse effects of the arch, which would be built at the foot of Arlington Memorial Cemetery across the Potomac River on National Park Service land.

The ACHP’s leadership and members are appointed by the president.

The law says federal officials don’t have to reach an agreement with state officials on mitigation of those harms, but they do have to try. Those consultations can then be unilaterally terminated if there’s a failure for parties to meet in the middle.

Virginia officials earlier this week said the arch will ‘mar’ the landscape at the foot of Arlington National Cemetery, located on the Virginia side of the Potomac River.

A letter sent Monday by Virginia’s Department of Historic Resources (DHR) to the National Park Service laid out the state officials’ concerns. 

“DHR anticipates all the proposed mitigation will do will further highlight how this undertaking has marred rather than added to these spaces,” wrote Samantha Henderson, the director of review and compliance at the agency.

Henderson wrote that NPS has received “numerous comments” from the public, as well as from related D.C. and Virginia agencies, about the arch, and that “[t]hese comments have not been directly addressed in a manner that shows NPS is consulting with the goal of seeking agreement where feasible.”

The Virginia officials said NPS has fallen short in multiple ways and that its proposal to minimize the harm to the arch “fails to address the severity of the adverse effects.”

Henderson said any interpretive materials installed at the arch site should “focus on the history that drove the need to build these commemorative spaces, the history of sacrifice and honor represented by Arlington National Cemetery and Arlington House, and how that past informs our use of these spaces now.”

Washington, D.C., officials declined to comment on the arch plan to ABC News.

ACHP said the Park Service has “stated that implementation of alternatives to avoid or minimize the adverse effects would alter the fundamental nature of the proposed undertaking and fail to achieve its goals.”

The federal preservation agency said it will forward its final comments to Interior Secretary Doug Burgum by Oct. 7. 

Burgum will then reach a determination on whether to move forward with the arch.

The project design has yet to receive final approval by the National Capital Planning Commission but is slated to be reviewed by that agency over the next six months.

In a post on his social media platform on Sunday, Trump said that, at the request of the U.S. military, he agreed to convert the arch into a “top grade Military Complex/Triumphal Arch, to house, store, and have the rapid ability to use large numbers of drones, plus Snipers, on both the roof and plaza areas, and additionally have and hold large quantities of sniper ammunition in storage.”

The Pentagon would not comment to ABC News on Trump’s announcement.

The Trump administration last week acknowledged that the arch will cause “adverse effects” on the setting and views, but those impacts “cannot be fully avoided” because the arch’s location is “central to the undertaking.”