WASHINGTON — Republicans hope to repeal major parts of the Affordable Care Act using an expedited procedure known as budget reconciliation.

The process is sometimes called arcane, but it has been used often in the past 35 years to write some of the nation’s most important laws. “Reconciliation is probably the most potent budget enforcement tool available to Congress for a large portion of the budget,” the Congressional Research Service, a nonpartisan arm of Congress, has said.

Here is a primer.

Q. What is the budget reconciliation process?

A. It is a way for Congress to speed action on legislation that changes taxes or spending, especially spending for entitlement programs like Medicare and Medicaid. Although conceived primarily as a way to reduce federal budget deficits, it has also been used to cut taxes and to create programs that increase spending — changes that can raise deficits.

In the Senate, a reconciliation bill can ordinarily be passed with a simple majority. For other bills, a 60-vote majority is often needed to limit debate and move to a final vote.