The Texas governor faces growing calls to drop a vehicle inspection program that has led to blockades and long queues at the Mexican border, threatening billions of dollars in trade at an already strained supply chain.

Mexican truckers have blocked major border crossings since Monday in protest against Governor Greg Abbott two paragraph letters last week. Transit times for commercial shipments have slowed to 10, 20 or even 30 hours in some cases, Mexican industry bodies said.

The dispute has jeopardized the movement of goods worth billions of dollars between the two countries.total more than $440 billion Annual trade flows through U.S. states through the Texas-Mexico border crossing, according to data from the Texas Frontier Economic and Enterprise Development Center at Texas A&M International University.

The business disruption comes amid a broader dispute over immigration between the Republican Abbott and Democrat Biden administrations.

Abbott said the additional inspections were aimed at deterring cross-border smuggling of migrants and drug trafficking, as well as improving vehicle security.He also framed them as Reply U.S. President Joe Biden has decided to end pandemic-related immigration deportations.

“This will significantly slow traffic from Mexico to Texas. It’s a byproduct of the cartel crossing the line,” Abbott said in a news conference last week.

The Texas Department of Public Safety said it had inspected 3,443 commercial vehicles within five days of Abbott’s order, and that 807 of them were taken out of service for safety violations.

Mexico’s foreign ministry said on Tuesday that trade flows at its four main ports of entry had fallen to about a third of normal levels, hurting the incomes and competitiveness of both countries, adding that it rejected the measures.

U.S. Customs and Border Protection on Tuesday called Texas’ new measures “unnecessary“And said protests in Mexico had halted all commercial traffic on the Farr International Bridge. Northbound freight traffic was also disrupted at the Isleta and Santa Teresa border crossings in New Mexico, it said.

The increased security checks have increased the time commercial vehicles have to enter U.S. states, further disrupting supply chains in industries ranging from agriculture to automobiles amid the stress caused by the pandemic.

“The execution of this order has caused severe disruption to our supply chain,” the Texas International Produce Association said in a letter this week. “It is damaging our business and the reputation of Texas.”

In some cases, these checks have caused transit delays for hours, with drivers often having to wait without food, water or bathrooms, several Mexican industry groups said.

Mexican National Cargo Chamber of Commerce Tuesday Calls for Abbott to end inspections to avoid a “collapse of international cross-border trade” estimated delays at the Pharr Bridge cost $8 million a day in damages.

Mexico’s National Agriculture Commission said it previously took about four hours for drivers to go through all necessary border checks in Texas. Since the new measures took effect, that time has risen to 30 hours in some cases.

The measures are designed to focus the federal government’s attention on immigration, said Raymond Robertson, director of the Mosbach Institute for Trade, Economics and Public Policy at Texas A&M University. Even many conservatives in the state’s business community are against them, he added.

“There are already a lot of conservative people who are lifelong Republicans who are very uncomfortable with what’s going on, and I think they’re going to put pressure on the governor,” he said.