One of the busiest trade ports on the US-Mexico border remained effectively closed Wednesday as frustrations and traffic jams grew over Texas Gov. Greg Abbott’s new orders requiring extra inspections of commercial trucks as part of the Republican’s sprawling border security operation.

Mexican truckers have been blocking the Pharr-Reynosa International Bridge since Monday in protest of Abbott’s order last week for state troopers to stop and inspect trucks entering Texas. Long lines have formed elsewhere along Texas’ roughly 1,200-mile (1,930-kilometer) border, with some lasting 12 hours or longer.

The Mexican government said Abbott’s order was causing “serious damage” to trade and that cross-border traffic had dropped to a third of normal levels just a week into the inspections. Abbott’s order, according to White House spokeswoman Jen Psaki, is “unnecessary and redundant.”

The stalemate is the result of an initiative that Abbott claims is necessary to combat human trafficking and drug trafficking. However, critics question how the inspections are accomplishing this goal, while business owners and experts complain of financial losses and warn that shortages could occur as soon as this week in the United States.

Texas Agriculture Commissioner Sid Miller, a Republican, called the inspections a “catastrophic policy” that is forcing some trucks to reroute hundreds of miles to Arizona.

The shutdowns and delays have sparked some of the most widespread criticism of Abbott’s multibillion-dollar border operation, which the two-term governor has made a centerpiece of his administration. Thousands of state troopers and National Guard members are already stationed along the border, and prisons have been converted into detention centers for migrants arrested on state trespassing charges.

Abbott warned last week that border inspections would “dramatically slow” border traffic, but he has yet to address the backlogs or port closures. A message seeking comment left with his office on Tuesday went unanswered, but the governor has scheduled a press conference for Wednesday afternoon in Laredo.

The disruptions at some of the world’s busiest international trade ports could endanger Abbott’s bid for a third term in office. During a stop in Pharr on Tuesday, Democrat Beto O’Rourke, a former presidential candidate who is running against Abbott for governor, said the inspections were doing nothing to stop the flow of migrants and were worsening supply chain issues.

Joe Arevalo, the owner of Keystone Cold, a cold-storage warehouse on the border, joined him. “They’ve never, ever, ever held up a complete system or a complete supply chain,” he said, despite the fact that Texas state troopers have always inspected some trucks crossing the border.

According to the National Freight Transportation Chamber, 3,000 trucks cross the Pharr bridge on a typical day. The Pharr Bridge is the largest land port for produce entering the United States, such as leafy green vegetables.

About two-thirds of the produce sold in Texas comes from Mexico.

The Texas Department of Public Safety is conducting the additional inspections. As of Monday, it had inspected more than 3,400 commercial vehicles and had placed more than 800 “out of service” for violations such as defective brakes, tires, and lighting. It didn’t say whether the truck inspections turned up any migrants or drugs.

The order’s impact quickly spread beyond Texas, with US Customs and Border Protection officials confirming another blockade at the Mexican customs facility at the Santa Teresa port of entry in southern New Mexico, not far from El Paso, on Tuesday. According to Jerry Pacheco, executive director of the International Business Accelerator and president of the Border Industrial Association, those protests are misguided because New Mexico has nothing to do with Texas’ inspection policies.

Professor Ed Anderson of the University of Texas at Austin’s McCombs School of Business compared the disruptions to those caused by a trucker strike in Canada in February, which forced auto plants on both sides of the border to shut down or reduce production. During that protest, trucks looking for other ways to enter the United States caused traffic congestion on other bridges, a scenario Anderson believes could happen again on the southern border.

Consumers will most likely notice the effects by the end of this week, according to Anderson.