The Senate Parliamentarian — the nonpartisan official who advises the upper chamber on the rules regarding legislative matters — has added to her previous list of concerns about the Republican bill to repeal and replace the Affordable Care Act, raising new concerns about the GOP’s ability to pass the legislation in its current state.

Most Senate bills require a 60-vote majority in order to get over the filibuster hump. However, budget resolutions are among those types of bills that can be passed with a simple 51-vote majority, but only is that budget resolution meets certain standards set forth in the so-called Byrd Rule.

In short, that rule says that budget resolutions can’t enact new government policies, and can’t stray too far from matters directly related to budgetary matters like taxes and expenditures.

Last week, Parliamentarian Elizabeth MacDonough flagged a number of items in the GOP’s Better Care Reconciliation Act that go beyond the guidelines of the Byrd Rule, like the decision to strip all Medicaid funding from Planned Parenthood or the plan to allow each state to determine how much of a health insurance company’s premiums must be spent on care of policy holders.

Today, Sen. Bernie Sanders (VT), Ranking Member of the Budget Committee, revealed that MacDonough has subsequently concluded that other aspects of the Republican legislation run afoul of the rules.

Among the BCRA items that cross this line, according to the Parliamentarian, is the proposal to allow insurers to charge significantly higher premiums to older Americans. Under current law, insurers can only charge their oldest policy holders up to three times the rate charged to younger customers. The GOP wants to let insurers charge older customers five times what they charge to younger customers.

This has been an aspect of both the House and Senate bills, and in all of its iterations the Congressional Budget Office has projected that this policy change could ultimately result in lower average premiums for customers, but older Americans — who are more likely to need insurance — would probably be paying much more than they would under current law.

Removing this aspect from the GOP bill could have cascading effects on the long-term effects of repeal. If insurance companies aren’t allowed to charge the even higher rates to older customers, they may not be able to offer more affordable plans to younger Americans, which could mean even more young adults choosing to go without insurance.

Another facet of the BCRA red-flagged by the Parliamentarian is the proposal to let small businesses establish “association health plans” that could then be sold across state lines. Such insurance plans could be exempt from the Essential Health Benefits requirements of the Affordable Care Act.

Speaking of essential benefits, MacDonough has yet to decide on the matter of granting waivers to states, allowing them to opt out of the Essential Health Benefits requirements and other Obamacare rules.

“This is legislation which impacts every American and one-sixth of our economy, yet this bill has been written behind closed doors, without a single hearing,” said Sanders. “One of the results of this absurd process is that many of the provisions in the latest Republican bill have been found to be in violation of Senate rules.”

The Parliamentarian’s ruling doesn’t force the GOP to remove these aspects of the bill. Supporters of the repeal movement have pointed out that Vice President Mike Pence, in his role as President of the Senate, could overrule MacDonough, though it’s been decades since a Vice President has done so. Additionally, there are concerns that ignoring the Parliamentarian would effectively set the precedent that the controlling party of the Senate can pass anything it wants with just 50 votes, so long as it’s labeled a “budget resolution.”

Earlier today, the Senate — with Pence as tiebreaker — voted to move forward on debate about the repeal and replace process, though it’s still unclear exactly what the Senate may ultimately try to pass at the end of this process.

The GOP is reportedly considering a “skinny” repeal bill that would get rid of the current requirement that everyone has insurance, or that employers of a certain size must offer coverage to workers. However, previous CBO scores on this sort of legislation have projected that it would result in higher premiums and many millions of additional Americans going without insurance.

UPDATE: In a late-night vote, the Senate fell several votes short in its efforts to accept the Better Care Reconciliation Act. Following the Parliamentarian’s guidance, that legislation would have needed 60 votes, but only received 43. More amendments and more votes to come as the week goes on.