NEW YORK (Reuters) – U.S. President Donald Trump said on Friday he plans changes to the H-1B program that grants temporary visas for specialty occupations such as technology or medicine, but his administration said later he was referring to changes that were proposed last year.

“H1-B (sic) holders in the United States can rest assured that changes are soon coming which will bring both simplicity and certainty to your stay, including a potential path to citizenship,” Trump said on Twitter. “We want to encourage talented and highly skilled people to pursue career options in the U.S.”

It was unclear what Trump meant by a “potential path to citizenship” for H-1B visa holders, who already are eligible to be sponsored by employers for legal permanent residency, which would then make them eligible to become U.S. citizens.

When asked about Trump’s tweet, U.S. Citizenship and Immigration Services spokesman Michael Bars provided a statement about a formal proposal in December for changes to the H-1B process, which are likely to become final later this year.

The proposal is designed to increase by 5,340, or 16 percent, the number of H-1B beneficiaries who hold advanced degrees from American universities. It would also streamline the application process with a new electronic registration system.

“These proposed regulatory changes would help ensure more of the best and brightest workers from around the world come to America under the H-1B program,” Bars said.

Critics questioned why Trump tweeted about a month-old proposal at a time when he is battling with congressional Democrats over spending legislation to fund the federal government. Trump wants to include $5.6 billion for a wall along the border with Mexico, which he says will stem illegal immigration.

Democrats call the proposed wall expensive, ineffective and immoral. The dispute has led to a partial shutdown of the U.S. government that is now in its 21st day.

Doug Rand, a former White House official in the Obama administration who worked on immigration issues, said the proposed changes to the lottery selection process were at best modest and at worst could cause chaos. Some immigration experts do not believe the new registration system will be ready in time for the next lottery, which occurs in the spring.

“The odds that a complicated new electronic processing system will be effectively launched by DHS in time for the next lottery on April 1 is low probability and has nothing to do with a potential path to citizenship,” Rand said.

Throughout his presidency, Trump has sought to stem illegal immigration and to deport more immigrants living in the United States illegally. His administration has also worked to limit legal immigration, including through a proposal that would penalize aspiring immigrants who use public benefits.

Trump has also derided visas granted to family members of U.S. residents or citizens as “chain migration,” and backed a Republican proposal in 2017 that would have slashed legal immigration in half.

“The devil is in the details, said Todd Schulte, president of FWD.us, a nonprofit group which advocates for pro-immigration policies. He said his group, which was founded by tech executives including Facebook founder Mark Zuckerberg, remains “skeptical of vague pronouncements given the administration’s track record.”

U.S. companies often use H-1B visas to hire graduate-level workers in specialized fields including information technology, medicine, engineering and mathematics. But the visa program has also drawn criticism for being used heavily by foreign outsourcing companies that squeeze out American firms.