(CNN) As President Donald Trump prepares to sell Congress on the border wall at Tuesday's State of the Union, a butterfly conservation group is putting itself in the way of construction set to begin in Texas.

Equipment for the construction of the first new miles of southern border wall approved since Trump took office has been staged in Texas' Rio Grande Valley region, a Customs and Border Protection official confirmed on Tuesday.

These first new miles of wall are funded with last year's congressional appropriations, and are part of two projects -- totaling 14 miles -- in the Rio Grande Valley that will be built in the location of an existing levee wall. While these will be new miles of wall, they are not part of the President's $5.7 billion push for wall construction, which triggered a standoff that led to the federal government's longest-ever shutdown last month

But the construction is running into opposition from the National Butterfly Center in Mission, Texas, a 100-acre wild butterfly habitat. The brewing fight on the border underscores the ugly political reality of the wall: Even if Trump wins wall money in Washington, the administration will still face an array of challenges to getting anything built.

A photo posted by the butterfly center appears to show one of the first excavation vehicles that will be used on the wall construction project. The CBP official could not confirm the photo, but did confirm that an excavator had been staged on US Fish and Wildlife Service property near the center.

The first excavator is parked on land "immediately to the east of us," the center posted on its Facebook page Sunday. According to the nonprofit, the local police department informed them that they will have "no access" to their "own land south of the levee" as of Monday.

"Effective Monday morning, it is all government land," the Mission Police Department officer told the center Sunday, according to the social media post.

CNN has reached out to the Mission Police Department for additional information.

The National Butterfly Center has been fighting the wall construction in court for more than a year, first filing suit in December 2017 against the Department of Homeland Security over the government's plans.

Executive Director Marianna Trevino-Wright told CNN that protesters have arrived to rally against the wall construction. She said more heavy equipment arrived in the area on Monday and she expects more protests "both for and against" the wall.

The center's lawsuit accuses the administration of violating environmental legislation and the Constitution while threatening to take property away from the butterfly center without "just compensation."

"The issue is not whether butterflies can fly over a wall, but whether private property (farms, businesses, homes) should be seized and destroyed for a project that does not serve the greater good or enhance national security," wrote the butterfly center in a GoFundMe posting in December.

The center is a 100-acre wildlife facility and botanical garden in South Texas that abuts the Rio Grande and is part of the US Fish and Wildlife Service Lower Rio Grande Wildlife Corridor, according to court documents.

According to the lawsuit, "proposed border wall construction would cut off two-thirds of the Butterfly Center, effectively destroying it and leaving behind a 70-acre no-man's land between the proposed border wall and the Rio Grande."

In a response to the lawsuit, government attorneys said Homeland Security Secretary Kirstjen Nielsen published an environmental waiver and found that certain areas within the Rio Grande Valley region, including the area along a levee running through the butterfly center's property, "are areas of high illegal entry and require construction of additional border infrastructure."

Trevino-Wright said the case in "languishing" in the courts and that she is exploring additional legal action.

There are 80 cases related to barrier construction from years past still outstanding, according to the Justice Department.

Over the past weekend, CBP announced in a press release that heavy equipment for the levee wall was on its way and might be seen entering the Rio Grande Valley as early as this week.

This is part of a 6-mile project in Hidalgo County, Texas, that was announced in November to construct and install a reinforced concrete levee wall to the height of the existing levee, as well as 18-foot-tall steel bollards on top of the concrete wall.

It will also include vegetation removal along a 150-foot zone, technology, lighting, video surveillance and an all-weather patrol road parallel to the levee wall.

The Rio Grande Valley region "remains an area of high illegal cross border activity," said the CBP press release at the time. "In FY 2017, (US Border Patrol) apprehended over 137,000 illegal aliens, and seized approximately 260,000 pounds of marijuana and approximately 1,192 pounds of cocaine" in the sector, added the release.

According to CBP, the walls system "will serve as a persistent impediment" to transnational criminal organizations, while still allowing river access for property owners.

CBP officials have previously said that construction on the first new miles of wall was slated to begin in Texas in February. There is no firm update on timing for the start of construction, the CBP official told CNN on Tuesday.