President Trump announced his support for a bill to cut legal immigration in half by 2027.

Flanked by Republican Sens. Tom Cotton of Arkansas and David Perdue of Georgia, Trump endorsed a bill they co-authored which would reduce the number of family members American citizens and legal residents can bring into the country and favor English-speaking and skilled workers.

“This legislation demonstrates our compassion for struggling American families who deserve an immigration system that puts their needs first and that puts America first,” he said.

Trump has long called for a crackdown on illegal immigration, but his stance on legal immigration has been much less clear. In May, he told The Economist that he supports legal immigration and was not looking to reduce the numbers.

Some Republican senators have already voiced skepticism about the plan.

“They want to cut back significantly on legal immigration and I don’t think that’s wise,” said Arizona Sen. Jeff Flake. “I think we ought to continue to be a welcoming nation.” Sen. Lindsey Graham said in a statement today that he opposes the proposed cap, saying it would be “devastating” to South Carolina’s economy, which “relies on this immigrant workforce.”

Called the Reforming American Immigration for Strong Employment Act or RAISE Act, the bill would limit family members who can apply for green card status to only spouses and minor children and streamline merit-based application in an attempt to limit the immigrant pool to only the most skilled and educated applicants. It would also eliminate the Diversity Visa Lottery and limit residency offers for refugees.

According to details from the February proposal, if enacted, the plan would reduce legal immigration to around 500,000 people a year by a decade from now, down by half from just over a million in 2015.

Proponents from immigration reform groups argue that the bill would reduce burdens on taxpayers by limiting the number of unskilled workers who enter the country, and “imbue our system with some meritocracy,” said Ira Mehlman, media director at the Federation for American Immigration Reform.

Opponents were sharply critical of the proposal, however.

Jeremy Robbins, executive director at the immigration think tank New American Economy, says that while encouraging skilled immigrants is a step in the right direction economically, reducing overall numbers is not. “Virtually every economist who looks at this is going to find that immigration is good for the economy,” Robbins said.

And while Trump and the bill’s advocates in Congress frequently point out that the proposed merit system takes some cues from Canada and Australia, where a similar point system is used, those systems don’t apply comparable caps on family immigration. That discrepancy would weaken RAISE’s economic benefits, according to Robbins.

“There’s a lot to admire about their systems, but that’s not in the bill,” he said.

Frank Sharry, executive director of the immigration reform group America’s Voice, said that the family cap would disproportionately affect Asian American immigrants, who tend to utilize the more varied existing green card categories, while elimination of the Diversity Lottery will disproportionately hurt African American and Caribbean immigrants who benefit from the measure.

Mark Krikorian, executive director of the pro-immigration reform Center for Immigration Studies said that even if the bill doesn’t make it through a belabored Congress, it’s a step in the right direction.

“You’ve got to start somewhere, and this is a really good start even if it doesn’t end up being enacted into law by this Congress,” he said.

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Write to Emma Talkoff at emma.talkoff@time.com.