Two senior Senate Republicans accused President Joe Biden of violating the law by holding up border wall construction that Congress specifically approved under the Trump administration, and they are pushing a government watchdog to force the White House's hand.

Sen. Shelley Moore Capito, the top Republican on the Senate Appropriations Subcommittee on Homeland Security, and Vice Chairman Sen. Richard Shelby of Alabama pushed Wednesday for the Government Accountability Office to intervene on the pot of money that Congress allocated for wall construction at the U.S.-Mexico border. Capito, along with 40 Republican senators, wrote GAO Comptroller Gene Dodaro in March, stating that Biden violated the Impoundment Control Act by suspending all Department of Homeland Security border wall projects without providing legal justification.

“The law does not permit the pause,” the senators wrote in the Wednesday letter on the basis that Biden never told Congress about a plan to cancel the funding amid his review of it or named a reason for delaying the funded projects.

If GAO issues an opinion, it could give Republicans grounds to sue Biden for holding up the projects, all while the southern border faces the highest number of illegal immigration attempts in 21 years.

Current external factors — namely, the most acute immigration crisis in recent memory — support expediting work on the border wall system, not halting it,” Capito and Shelby wrote. “Each day this impoundment continues, funds lawfully appropriated for border wall construction are cynically under-executed and a reserve is growing."

Shortly after taking office in January, Biden suspended all border wall construction. For construction, $4 billion had been funded by Congress during the Trump administration, and $10.5 billion had been diverted from the Department of Defense by President Donald Trump after lawmakers refused to give him $18 billion for the projects.

By the time Trump left office, more than 450 miles of wall was completed, though most of it was duplicate fencing or replaced shorter barriers. A remaining 290 miles was to be finished with the remaining money, but in April, the Pentagon said it would take back whatever Trump had not used.

“While DHS announced on April 30, 2021, that it was lifting the pause in two isolated cases, all other construction across the southwest border — from South Texas to the San Diego shoreline — remains unlawfully halted,” Capito and Shelby wrote in the letter.

The delays in finishing portions of border wall in Arizona, California, New Mexico, and Texas have also affected normal replacement projects that were completed under the Obama, Bush, and Clinton administrations and had been slated for improvements.

“Incomplete installations have left gaps in the border wall system, both seen and unseen. Breaks in the physical infrastructure serve as funnels for illegal crossing, human trafficking, and drug smuggling; create environmental hazards; and unnecessarily tax our Border Patrol agents, who have to sit post at these breaks around the clock,” the letter states. “Additionally, ground sensing technology and cameras that enhance the operational effectiveness of the physical barriers await installation or, worse, are installed but not turned on.”