His comments Wednesday night highlighted a major issue facing the technology sector: Should American tech companies scour the globe to import the most qualified technicians or pay top dollar for American engineers?
Those are the questions surrounding the H1-B visa program, a practice of granting U.S. immigration and residency rights to foreign workers qualified in so-called "specialty occupations."
Zuckerberg has said he supports increasing the number of these visas, while Trump's website declared the program encourages Silicon Valley companies to pass over black, Hispanic and female workers.
"We graduate two times more Americans with STEM degrees each year than find STEM jobs, yet as much as two-thirds of entry-level hiring for IT jobs is accomplished through the H-1B program," Trump's campaign website reads. "More than half of H-1B visas are issued for the program's lowest allowable wage level, and more than eighty percent for its bottom two. Raising the prevailing wage paid to H-1Bs will force companies to give these coveted entry-level jobs to the existing domestic pool of unemployed native and immigrant workers in the U.S., instead of flying in cheaper workers from overseas."
U.S. employers can grant a total of 65,000 H-1B visas annually to workers like scientists, engineers or computer programmers, with some exceptions for those employed at nonprofits, government or higher education, according to the U.S. Department of Homeland Security website. Applicants must have an advanced degree in their field, and the extensive applications cost employers and immigrants several hundred dollars.
There are dueling narratives in the research on the costs and benefits of the H-1B program.
Some research shows that H-1B holders actually earn more than their domestic counterparts — but about 25 percent are granted for occupations that typically require only an associate's degree, according to think tank Brookings Institution. More recent research, though, suggests the program is used to cut labor costs, according to the Economic Policy Institute.
Zuckerberg has called for the cap to increase, founding an advocacy group bolstered by other technology heavy hitters like LinkedIn founder Reid Hoffman, Alphabet's Eric Schmidt, and Yahoo's Marissa Mayer.
"Why do we offer so few H-1B visas for talented specialists that the supply runs out within days of becoming available each year, even though we know each of these jobs will create two or three more American jobs in return?" Zuckerberg wrote in The Washington Post in 2013. "Why don't we let entrepreneurs move here when they have what it takes to start companies that will create even more jobs?"
At the debate, Trump backpeddled on his campaign website's rhetoric, saying he supports Zuckerberg's efforts.
"We're losing some of the most talented people. They go to Harvard; they go to Yale; they go to Princeton. They come from another country and they are immediately sent out. I am all in favor of keeping these talented people here so they can go to work in Silicon Valley."
Fellow Republican candidate Marco Rubio doesn't highlight his immigration plan on his campaign website, but bills himself as a tech-savvy candidate in favor of trends like the sharing economy and a tax-free Internet. That, combined with proposed visa legislation, led Trump's campaign to call Rubio "Mark Zuckerberg's personal Senator."
"In 2015, we have a very different economy," Rubio said in the debate. "Our legal immigration system from now on has to be merit based. It has to be based on what skills you have, what you can contribute economically, and most important of all, on whether or not you're coming here to become an American; not just live in America, but be an American."