CEOs of some of the country’s largest companies have contacted President Trump on Wednesday claiming his restrictive immigration policies may have serious negative impacts on America’s overall economy.

Members of Business Roundtable, including Apple’s Tim Cook, Salesforce’s Marc Benioff, and PepsiCo’s Indra Nooyi, sent a message to the Trump administration explaining the implications shortage of green cards for workers could have on American businesses. The CEOs complained regarding how the incessant changes to immigration criteria was heightening costs for employers and employees seeking working visas alike.

Throughout the past year, the Trump administration has been denying more work visas than it did in 2016 as well as delaying approvals which has turned into a major headache for employers in need of foreign talent. Processing times for H1-B visas have also increased significantly.

“There have been delays in processing that we have not felt before,” explained Dr. Andre C. Yacht, chief academic officer at Northwell.

The letter sent to the administration by the Business roundtable emphasized how, “inconsistent immigration policies are unfair and discourage talented and high skilled individuals from pursuing career opportunities in the United States.”

According to the New York Times, The Trump administration is using the United States’ immigration policy to “constrict the flow of foreign workers into the United States by throwing up roadblocks to limit legal arrivals.”

The changes to policy began in April 2017, when Trump issued the “Buy American and Hire American” executive order which called on the heads of all agencies to “rigorously enforce and administer the laws governing entry into the United states of workers from abroad.”

According to data provided by the National Foundation for American Policy, denial rates for H-1B visas escalated to 41 percent in the past three months. Experts believe that as baby boomers begin to retire, and immigration laws get more and more restrictive, colossal gaps could emerge in the job market.

Francine D. Blau, an economist at Cornell, advised that “a lot of labor-force growth comes from immigrants and their children. Without them, we’d suffer the problems associated with countries with an aging population, like Japan.”

Members from the Business Rountable share Blau’s concerns. “At a time when the number of job vacancies are reaching historic highs due to labor shortages, now is not the time to restrict access to talent,” read their letter.

In his executive order, however, President Trump ensures the new immigration policies are meant to protect the interest of the American workforce and prevent acts of fraud or abuse within the United states’ immigration system.