FIRST ON FOX: More than 30 House Republicans are urging the Biden administration to end COVID-19 vaccine mandates for truckers and agricultural workers coming across the U.S. border, warning that the mandates risk having a "catastrophic effect" on the supply chain crisis.

The Department of Homeland Security in January began requiring non-U.S.citizens coming across the border via ports of entry to show proof of vaccination against COVID-19. That includes truck drivers and workers coming across on H-2A temporary agricultural worker visas.

GOP SENATORS RENEW EFFORTS TO DEFUND BIDEN'S VACCINE MANDATES 

While cities across the country, including those with vaccine mandates, have started rolling back COVID-19 restrictions, there are no signs they will be relaxed at the border -- including ports of entry. COVID-19 restrictions also remain in place for those crossing the border illegally in the form of Title 42.

A convoy of trucks and other vehicles travels the I-495 Capital Beltway near the Woodrow Wilson Bridge, to protest mandates and other issues, Sunday, March, 6, 2022, in Fort Washington, Maryland. (AP Photo/Alex Brandon)

In a letter to Secretary of Homeland Security Alejadro Mayorkas, 36 lawmakers led by Rep. Ralph Norman, R-S.C. point out the ongoing supply chain crisis and the worker shortage the country is currently facing, which requires an increase in the number of agricultural workers being brought into the U.S.

"Now that these H-2A workers are required to be fully vaccinated to enter the U.S., we have heard from numerous farmers and constituents who worry that these new vaccination requirements are delaying and will continue to delay the arrival of H-2A workers this year," the lawmakers wrote. "These limitations and delays will have a catastrophic impact on our already fragile supply chain and proliferate rising food prices."

Many H-2A workers come from Mexico, and the lawmakers argue that vaccine availability varies widely across Mexico, and some of the vaccines available are not accepted by the U.S. The lawmakers urge the Biden administration to allow for an exemption for that reason.

"Despite the historic supply and labor shortages, the Biden administration has upheld this restrictive vaccine mandate," Norman told Fox News in a statement. "Agricultural employers already depend on nonimmigrant foreign workers to fill domestic labor shortages. This policy does little to mitigate the spread of the virus and hurts essential industries along the way."

In this July 1, 2021 photo, farmworkers till soil as a heat wave bakes the Pacific Northwest in record-high temperatures near St. Paul, Oregon. (AP Photo/Nathan Howard, File)

Additionally, the lawmakers highlight the importance of foreign truckers in being the "backbone of America’s supply chain." Truckers in Canada have organized mass protests over the country’s vaccine mandates, and truckers in the U.S. are planning on making similar demonstrations over the cross-border vaccine regulations.

"While in the midst of a global pandemic and supply chain crisis, we must ensure necessary cross-border operations to bring essential goods into the U.S. are unhindered and stabilized," the Republican lawmakers argue in the letter.

CLICK HERE TO GET THE FOX NEWS APP

The Republicans urge the administration to allow flexibility for employers and employees on the restrictions.

The letter marks the latest instance of Republicans pushing back against vaccine mandates imposed by the federal government. Last month in the Senate, lawmakers rallied against a continuing resolution, demanding a vote first on an amendment to end various federal mandates.