The Byrd Rule, adopted in 1985, is a procedural constraint named after the late Senator Robert C. Byrd of West Virginia to prohibit “extraneous” provisions from being tacked onto reconciliation bills, which are fast-tracked budget packages that allow legislation to pass with a simple majority, bypassing the 60-vote filibuster threshold.

Senate Majority Leader John Thune, House Speaker Mike Johnson and administration officials are pressing Republican lawmakers to pass the One Big Beautiful Bill Act so Trump can sign it into law before the July 4 U.