Apple Chief Executive Officer Tim Cook greets customers at the grand opening of the new Apple Carnegie Library store in Washington, May 11, 2019.

Apple CEO Tim Cook on Thursday encouraged the U.S. Senate to pass legislation that would phase out per-country limits on green cards.

"Immigrants make this country stronger and our economy more dynamic. As a first step toward needed comprehensive reform, I urge the Senate to move quickly to pass the Fairness for High-Skilled Immigrants Act," Cook tweeted. "The contributions of these workers are critical to America's future."

Tweet.

The support for the stalled legislation is both a sign of Cook's personal interest in immigration policy as well as Apple's interest in making immigration easier for many of its employees who live in California but often face challenges obtaining a green card.

The Fairness for High-Skilled Immigrants act passed the House in September by a vote of 365-65 and now needs to be passed in the Senate and approved by the president before it goes into effect. It's been referred to the Senate Judiciary committee but no vote is scheduled.

The legislation, if passed, would substantially change the current immigration system by eliminating a per-country cap that advocates say effectively makes it harder to immigrate from a bigger country versus a smaller country. Many migrants with visas face long backlogs to get permission to permanently immigrate, called a green card.

"We have over 300 folks here on DACA, and we have several people that are on H-1Bs [visas] that might be deep in the green-card backlog," Cook said in a speech last summer.

The bill aims to equalize wait times across countries by changing the system to first-come first-served. According to the Cato Institute, a substantial portion of immigrants stuck in the backlog are skilled immigrants from China and India.

"Under the per-country cap system, immigrants from larger countries are only eligible to receive the same number of green cards annually as immigrants from smaller countries. As a result, the wait times for immigrants from larger countries have grown and grown, decade after decade, with no end in sight," Mike Lee, a Republican from Utah who sponsored the bill, said in a speech in September.

"The employment-based visa system is supposed to enable American businesses to bring the best and the brightest to this country," Lee continued. "Yet under the per-country caps, a factor that has nothing to do with a person's skills or merit distorts the recruitment process. This weakens the merits-based portion of our immigration system."

Cook sometimes takes political positions on topics like immigration and climate change. He's previously opposed Trump administration immigration policy, and earlier this year, signed his name to a Supreme Court brief opposing Trump's bid to terminate DACA, the Obama-era program that shields some immigrants without documentation from being deported.

The full bill can be read here.