The Trump administration on Wednesday filed an emergency application with the U.S. Supreme Court, asking the justices to set aside a lower court order that has stopped construction of border barriers through the Big Bend region of Texas.

The order is a significant obstacle for one of President Donald Trump's signature initiatives. The administration has been moving quickly to build walls and related infrastructure along the southern border from the Pacific Ocean to the Gulf of Mexico.

Local opposition and the October injunction

In Big Bend, the project has drawn pushback from ranchers, residents, business owners and environmental groups. They contend that the plan, which combines walls, vehicle barriers and surveillance technology, wastes money in a region where illegal crossings have historically been low, and that construction threatens the area's landscapes. Opponents have brought several lawsuits challenging the work.

In one of those cases, U.S. District Judge Kathleen Cardone on Oct. 2 issued a preliminary injunction halting construction across the roughly 500-mile project area while the litigation continues. The order covers Big Bend National Park as well as state-owned and privately owned land upriver and downriver from the park. Opposition had been building for months but intensified in August, when bulldozers were seen clearing land inside the national park.

The waiver dispute

At the center of the case are broad waivers issued by the Secretary of Homeland Security that let U.S. Customs and Border Protection skip environmental and other regulatory requirements that would otherwise slow a project of this size.

The government maintains that Big Bend sees a high level of illegal entry and that a 1996 law expressly gives the secretary authority to waive such rules when needed to build barriers and roads near the border. Challengers counter that Congress limited that power to areas of high illegal entry, and that the remote, rugged Big Bend region does not qualify.

Judge Cardone agreed with the challengers, finding that they "are likely to succeed on the merits of their major questions doctrine claim that the Big Bend Waivers were issued in excess of the Secretary's authority."

What is at stake

Trump has long promised a wall along the approximately 2,000-mile southwest border. Last summer, congressional Republicans provided the Department of Homeland Security with $46 billion to complete it, using a combination of 30-foot steel bollard walls, vehicle barriers and surveillance systems.

The administration warns that if Big Bend remains one of the few stretches without barriers, illegal crossings could shift there. Opponents respond that drones, surveillance towers and similar tools would be equally effective at a far lower cost than a wall.