Senate Majority Leader Mitch McConnell (right) with Sens. John Thune (middle) and Tom Cotton AP

Republicans trying to get the Better Care Reconciliation Act passed through the Senate could have their plans thwarted by the chamber's rules.

The Senate parliamentarian said Friday that major provisions of the Republican legislation would require 60 votes to advance, putting the already troubled legislation in further peril.

Passed in 1985, the Byrd rule says that any bill going through the budget reconciliation process — like the BCRA — can be blocked on the grounds that it contains an "extraneous matter" or something "merely incidental" to the federal budget.

The budget-reconciliation maneuver through which the GOP hopes to move the BCRA allows a bill that adjusts the federal budget to pass through the Senate with a simple 50-vote majority to avoid a filibuster. Any other legislation needs 60 votes to avoid a filibuster.

Key parts of the bill — including a plan to defund Planned Parenthood, restricting federal tax credits from being used for abortions, and a provision that would make people wait six months for health insurance if they have a lapse in coverage — all require 60 votes, according to the Senate parliamentarian. Republicans currently have 52 seats in the Senate.

"Should the Senate proceed to the bill, these provisions may be struck from the legislation absent 60 votes," the Senate budget office said.

Here are all the parts of the BCRA that could put the bill in jeopardy

The plan to defund Planned Parenthood

A provision that would restrict the use of tax credits for abortions.

Getting rid of the essential health benefits for Medicaid in 2020.

How the bill deals with cost-sharing subsidies

The section that locks individuals out of the insurance marketplace for six months if they don't have continuous coverage.

The medical loss ratio.

The provision that allows states that haven't used all of their block grants for health coverage for non-health purposes.

Changes to the Medicaid waiver system by prioritizing HCBS waivers.

A provision that requires a report regarding CMS-64 and Transformed Medicaid Statistical Information System data.

Here's the full list of the BCRA provisions that pass and don't pass the Byrd rule, as well as a few that are still under review.