(NewsNation) — Under a new program, the United States is accepting 100,000 Ukrainian refugees fleeing the Russian invasion of their country for up to two years.

According to the Department of Homeland Security, Ukrainians participating in “Uniting for Ukraine” must have a supporter in the United States who agrees to give them financial support while they stay in the U.S.

To prove they can do so, the U.S. sponsor has to file a Form I-134, or declaration of financial support, with U.S. Citizenship and Immigration Services. To protect against exploitation and abuse, the Department of Homeland Security said supporters will be vetted.

An American has to apply on behalf of Ukrainians, but if the U.S. sponsor is approved, migrants can then finish the application.

Virtually anyone in the United States with legal status, including those with green cards, can sponsor them. But Ukrainian citizens will need to pass security checks and prove they are vaccinated for measles, polio and COVID.

To be eligible for Uniting For Ukraine, refugees need to have fled the country right before or during the war.

It’s not clear how long the application process will take, but the Biden administration says processing time will be much faster than a normal refugee application.

Refugee advocates had been urging Biden’s administration to expedite its admission of Ukrainians, and have welcomed the announcement of the program. It also has public support: 82% of Americans say they favor providing humanitarian support to refugees from Ukraine, according to a poll from The Associated Press-NORC Center for Public Affairs Research. In a NewsNation poll from March, about 41% of people said the U.S. needs to do more to aid Ukraine as well.

The Associated Press contributed to this article.