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.

While the two bills are similar on the major tax provisions, how they work out their differences in the coming weeks will determine how quickly they can get a final product over the finish line. President Donald Trump is pushing to have the legislation on his desk by July 4th.

Provisions related to food aid and the consumer-protection agency are set to get dropped from the final bill after “Byrd bath.”