Tech companies are further ratcheting up the pressure on the federal government over H-1B visa reform.

Earlier this month, Compete America, an industry group that includes Amazon, Google, and Facebook, argued that the changes to visa policy lack necessary clarity. It also railed against what it called a “dramatic increase” in the percentage of H-1B applications denied or delayed.

According to the Seattle Times, Compete America wants the Department of Homeland Security and United States Citizenship and Immigration Services (USCIS) to review current practices and communicate better with “the regulated community,” i.e., all those tech firms that leverage the H-1B visa to fill their offices.

The full letter is available on the group’s website (PDF). “These reported shifts in agency action have been perplexing to our coalition’s members,” reads one part, “especially because the agency’s changes in approach were unannounced and unexplained and are not previewed in the regulations governing a qualifying H-1B specialty occupation that have been in effect since 1991.”

This isn’t the first time an industry advocacy group has swatted at the federal government over H-1B. In October, ITServe Alliance, a nonprofit group that counts more than 1,000 IT service organizations as its members, filed a lawsuit against USCIS, arguing that it approved the visas for too short a period.

For its part, the Trump administration is rumored to be working on reforms to the H-1B lottery system. According to Politico, which obtained its information from an anonymous official in the Department of Homeland Security (DHS), these reforms would see all H-1B applicants entering the same “general pool” of 65,000 visas. Once that pool is filled, any remaining applicants with advanced degrees would be diverted to a 20,000-visa “master’s cap” pool. At least on paper, this would increase the number of H-1B visa holders with advanced degrees, giving them two shots at a successful application.

Those plans have yet to be officially revealed, though, and in the meantime the Trump administration has imposed a temporary suspension on premium H-1B processing (it’s slated to run through February 2019). That was ostensibly put in place to allow USCIS time to clear through a backlog of petitions, and it’s proven a source of aggravation for some tech firms. Whether it will make further adjustments based on tech companies’ pushback is an open question.