The reconciliation process lets Republicans push the bill through the Senate—where they have a 53-47 majority—on a simple majority vote. But the process comes with strings attached, and those limits are known as the Byrd Rule, for the late Sen. Robert Byrd (D., W.Va.).

Republican leaders are relying on the Medicaid provider tax change to save billions of dollars in the GOP package to offset the cost of trillions of dollars in tax cuts that are their top