With the Senate voting on the future of health care this week, a lesser-known governmental advisory office is warning the GOP that they may not get the outcome they want, based on a parliamentary law known as the “Byrd rule.”

The US Senate’s Office of the Parliamentarian has warned the Senate this week that the anti-abortion provisions that have been added to the Better Care Reconciliation Act (BCRA) violate the Byrd rule, which states that any plans to use budget “reconciliation” would mean enacting the rule, requiring a 60-person majority vote in order to reach a minimum threshold for passing the law, not the 51 votes the GOP-lead Senate is hoping for.

The BCRA has budgeted to defund Planned Parenthood and withhold tax credits for 12 months, considered by the Office of the Parliamentarian to be motivated not by budgetary reasons but by a political agenda, meaning that the 60-vote minimum is mandatory under the law.

When the GOP plans to use budget reconciliation, what they are actually saying in the bill is that they want to be able to avoid debating this incidental budget line item on the Senate floor. The Atlantic explains, “Reconciliation legislation can only include changes to laws that directly affect the federal budget, and can be scored by the Congressional Budget Office. So for example, Republicans could ‘repeal’ Obamacare premium tax credits via reconciliation by making the credit $0 for everyone, but couldn’t in theory use the same bill to eliminate the requirement for insurers that take premium tax credits to also take people with pre-existing conditions.”

This poses a major obstacle for the GOP, as they currently do not have a strong-enough majority, with at least two Senators speaking out against voting in favor of any current versions of health care reform, and John McCain out being treated for brain cancer. With no members of the Democratic caucus willing to vote across the aisle, this could be the end of any ability the GOP had to completely gut the current healthcare system.

Do you think the GOP-held Senate will heed the Byrd rule? Tell us @BritandCo!

(h/t Refnery29; photos via Getty)