Friday is the start of the annual window during which companies can apply for the limited number of H-1B visas for highly skilled foreign workers. There’s a cap on the number of visas awarded—65,000 for foreigners with a degree from any university, plus 20,000 for advanced-degree holders who’ve graduated from U.S. schools.

The number of submissions will likely surpass the 85,000 quota in a matter of days—as it did in both 2015 and 2014—which will trigger a computer generated lottery system where visas are awarded to applicants at random. Last year, U.S. Citizenship and Immigration Services received nearly 233,000 H-1B petitions during the first seven days of the filing period.

Employers, especially those in the technology and science fields, say that demand for the visas reflects a skills shortage in the U.S. They must recruit foreign workers for highly technical jobs because they can’t find qualified candidates in the U.S. Some companies have supported a higher cap on the number of H-1Bs awarded; 85,000, they say, is simply not enough. Facebook CEO Mark Zuckerberg has been an especially vocal advocate for raising the limit.

Yet there are opponents of the program who are just as adamant. From their perspective, the system robs Americans of jobs and replaces them with cheaper, foreign labor. That claim is at the heart of a lawsuit filed two ex-Disney employers who sued the entertainment behemoth in January, claiming that the company violated the law by using H-1B visas to use foreign workers even though they would displace American employees. Disney has denied the allegations.

That case also illustrates how outsourcing companies—armed with brigades of lawyers—are winning an outsize share of H-1Bs by going big in what’s become a numbers game. When visas are awarded through a lottery, a company’s odds of winning improve the more applications it files—à la buying tickets for a Lotto or Powerball drawing. Thirteen global outsourcing companies were among the 20 firms that received the most H-1B visas in 2014, according to the New York Times, which cited the analysis of federal records by Howard University professor Ronil Hira.

The controversy surrounding the program has spilled into the presidential debate, and candidates have aligned themselves on either side of the argument. Hillary Clinton supports the system. Her opponent, Bernie Sanders, wants to raise the minimum wage of H-1B workers, which is seen as a way of discouraging businesses from using the visas. In the past, Republican candidate Ted Cruz had supported quintupling the number of H-1B visas available, but on the campaign trail, he’s called for the suspension of the program to enact reforms that better protect workers. And GOP frontrunner Donald Trump has opposed the program, except for a few comments he made during a debate in which he said the U.S. needed more foreign workers.