If Congress fails to move before the end of the year, Senate sources say, the chances of getting the entire plan over the finish line reduce dramatically.

Congressional leaders are hoping to muster a supplemental package to aid the war efforts in Ukraine and Israel, as well as make improvements to the U.S. immigration system, by the end of the year, according to multiple people involved in discussions.

The ambitious timeline would mean striking a deal that satisfies the funding requested by the Department of Defense to aid conflict zones, while simultaneously crafting an immigration package that not only provides resources for border security but includes a suite of policy changes to appease conservatives without alienating progressive Democrats.