At some 887 pages, the legislation is a sprawling collection of tax breaks, spending cuts and other Republican priorities, including new money for national defense and deportations.

Lawmakers voted largely along party lines to advance the megabill, overcoming weeks of closed-door negotiations and internal disagreements.

With Sens. Rand Paul and Thom Tillis opposed to the package, GOP leaders can afford only one more defection. And multiple Republicans aren't yet sold on the measure.