The Department of Housing and Urban Development proposed a rule Wednesday that would end public housing aid for undocumented immigrants.

An administration official told The New York Times that the rule would ensure that only American citizens receive housing assistance from HUD, putting an end to a loophole that did not require some aid recipients to prove citizenship.

While the move is one of several the Trump administration has taken to crack down on undocumented immigration, the official told the Times that the department was prompted to act by the long waiting list for public housing.

The rule proposes the use of the Department of Homeland Security’s Systematic Alien Verification for Entitlements Program, or SAVE program, to verify the citizenship of all members living in a household that receives assistance. Undocumented immigrants currently living in public housing would have up to 18 months to relocate.

The Times estimated that as many as 25,000 households could be affected.

Presumably in response to new of the proposed rule, HUD Secretary Ben Carson tweeted the following statement Thursday morning:

“Thanks to @realDonaldTrump's leadership, we are putting America's most vulnerable first. Our nation faces affordable housing challenges and hundreds of thousands of citizens are waiting for many years on waitlists to get housing assistance.”

But others did not view it that way.

Democratic presidential candidate Julián Castro, who was the HUD secretary under President Barack Obama, criticized the rule, the Times reported.

“Once again, the Trump administration is using the immigrant community as a punching bag to distract his base from his own political troubles,” Castro said. “The bottom line is that our government is terrorizing families – first with ICE raids, now with evictions.”

The rule was submitted to Congress on Wednesday for a 15-day review period, after which HUD will issue an open request for comment.