Democrats will need to prove to the parliamentarian, a former immigration lawyer, that the proposal satisfies Senate budget requirements, such as demonstrating an impact on federal spending, revenues or the debt. Democrats are discussing including a pathway to citizenship for DACA recipients, Temporary Protected Status holders, farmworkers and other immigrants deemed essential workers in the pandemic.

The parliamentarian has ruled against Democratic priorities before. Earlier this year, she rejected the party's proposal to raise the minimum wage to $15 an hour in their $1.9 trillion pandemic relief bill.

In addition to wanting to fulfill a key campaign promise, Democrats say that the need for the legislation coincides with the fate of the Obama-era Deferred Action for Childhood Arrivals program remaining in legal limbo. In July, a federal judge in Texas ruled the program was unlawful and blocked the Biden administration from approving new applications.

Democrats also argue there is some precedent for including immigration reform in a reconciliation package, highlighting GOP-led legislation from 2005 that included a provision related to the backlog of visas.

Sabrina Rodriguez contributed to this report.