On Friday, Senate Democrats  released a list of provisions in the Republican health-care bill that the Senate parliamentarian holds can pass via a simple, filibuster-proof majority vote. Among those provisions that didn’t meet her scrutiny are the bill’s plans to defund Planned Parenthood, restrict tax-credit funding for insurance plans that provide abortions, and a six-month “lockout” period from purchasing insurance for people who don’t maintain continuous coverage.

If this preliminary guidance holds, the Better Care Reconciliation Act—which is already in dire straits—seems likely to fail.

The final assessment of the parliamentarian, Elizabeth MacDonough, is a critical step in the GOP’s strategy for passing their bill to repeal and replace Obamacare. Republicans have opted to pass their health-care legislation via the special reconciliation process, under which they can cut debate short in the Senate and thus eliminate indefinite filibusters, which Democrats would certainly use in order to block any attempt to repeal Obamacare. But bills have to follow a certain procedure—called the Byrd Rule—in order to pass by reconciliation.

Broadly, the Byrd rule states that 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.

In practice, the parliamentarian reviews every provision of a reconciliation bill and outlines which ones pass muster under the Byrd rule by her own judgment. In this instance, according to the Democratic outline, MacDonough’s office ruled that “abortion restrictions on the premium tax credit and the small business tax credit, and the language defunding Planned Parenthood, violate the Byrd Rule.” Additionally, other provisions on the chopping block include the BCRA’s six-month continuous-coverage lockout, and its sunset of minimum requirements for alternative private-administered Medicaid plans.

Still under review are the BCRA’s provisions that allow states to waive certain essential health benefits for exchange plans, increase the age-rating scheme for older adults, and allow Medicaid funding to go to states in lump sum “block grants.”

Notably, all of these provisions that have either been challenged by the parliamentarian’s office or still await a final determination are those that were included in the BCRA to gain the support of hard-core conservatives, who, like their counterpart moderate faction have often criticized the bill and could harpoon any legislative action. It’s hard to see how a bill that retains Planned Parenthood funding and the use of premium tax-credits for plans that cover abortion would proceed to debate through conservative objections.

There is hope among the backers of the bill that the parliamentarian’s guidance would allow them to rewrite the key provisions in a way that would allow them to pass the Byrd rule. But the clock is ticking, and substantive rewrites might have to pass CBO review again, and the CBO has been a thorn in Republicans’ side over the past few weeks.

Some Republicans are hinting at more radical steps to get past MacDonough’s review. Senator Ted Cruz of Texas has been floating the idea of simply ignoring the parliamentarian’s review for months now. The presiding officer of the Senate—Vice President Mike Pence—technically makes the final call on parliamentary procedures, and could overrule the parliamentarian’s objections, although this would be a highly controversial break of Senate norms that hasn’t been attempted for over 40 years.

But this seems to be the era of flouting norms, as evidenced by the increasing willingness of Senate Republicans to challenge the CBO scoring process, and perhaps even consider the filibuster “nuclear option.” It’s hard to rule anything out at this stage.