CNN  — 

A group of US citizens and a nonprofit organization sued the Trump administration this week over a proclamation that would deny visas to immigrants unless they can prove they will have health insurance.

The lawsuit, filed in US District Court in Portland, Oregon, claims that the proclamation will bar hundreds of thousands of immigrants from coming to the United States, and as a result, could separate families who are immigrating via family-sponsored visas.

“Indeed, the Proclamation is unprecedented in its scope and impact, the largest ever suspension on the entry of immigrants of its kind,” states the lawsuit, which was brought by seven US citizens and Latino Network, an advocacy organization based in Oregon.

The proclamation is among a string of sweeping changes that could dramatically curb legal immigration to the United States. Earlier this month, President Donald Trump issued the proclamation, saying, “immigrants who enter this country should not further saddle our healthcare system, and subsequently American taxpayers, with higher costs.”

Visa applicants will have to prove to consular officials that they will be covered by an approved health insurance within 30 days of entry into the US or possess the financial means to “pay for reasonably foreseeable medical costs.” The new requirement could make it more difficult for people – particularly ones without financial means – to immigrate to the US.

Accepted health insurance includes employer-sponsored and family coverage plans, unsubsidized individual health plans, and short-term plans. Medicaid or Affordable Care Act subsidies do not qualify as “approved health insurance” under the proclamation.

The Justice Department did not immediately return a request for comment.

Exceptions to the rule include children of US citizens, unaccompanied minors, permanent residents who are returning to the US after being overseas less than a year, and “special immigrant visas” for Iraqi and Afghan nationals who worked for the US government, and their families. Immigrants with a valid visa issued before the proclamation’s effective date are also exempt, and the proclamation does not affect refugees and asylum seekers.

Advocates have also noted the irony that the proclamation requires immigrants to have health insurance, but not American citizens and legal residents. Trump often touts the fact that Congress essentially eliminated the Affordable Care Act’s individual mandate – which he has called “cruel” – by reducing the penalty to $0 as part of the 2017 tax cut law.

“Healthcare providers and taxpayers bear substantial costs in paying for medical expenses incurred by people who lack health insurance or the ability to pay for their healthcare,” the proclamation reads.

Former President Barack Obama used a similar argument to fight to include the individual mandate in his landmark health reform law.

The lawsuit notes the challenges immigrants may face and cites the administration’s public charge rule that makes it more difficult for immigrants who rely on government assistance like Medicaid, subsidized housing and food stamps to obtain legal status.

CNN’s Veronica Stracqualursi contributed to this report.