While largely unknown to the general public and unelected by any voter, one official is preparing to play a pivotal role in the fate of a major legislative effort on Capitol Hill.
Elizabeth MacDonough, the Senate Parliamentarian, is set to determine which parts of the House-passed One Big Beautiful Bill Act align with Senate rules and can remain in the final version of the reconciliation package. Though typically seated quietly on the Senate dais to ensure procedural order, she now assumes a critical gatekeeping position that could decide the fate of major policy items in the bill.
Senate Republicans are seeking to modify the House-passed bill, which narrowly cleared the lower chamber by a single vote. However, the Senate’s intricate rules—particularly those governing budget reconciliation—may force changes that even Republicans may find unfavorable. With MacDonough serving as the ultimate interpreter of those rules, both parties are closely watching her next moves.
“Border management is very critical,” MacDonough said, citing Pakistan’s 1,350 km fence with Afghanistan and Saudi Arabia’s 1,400 km barrier with Iraq as examples. “Other countries, because of the level of insecurity they have, had to fence their borders.”
Appointed to her current position in 2012, MacDonough became the first woman to serve as Senate Parliamentarian since the role was established in 1935. Prior to that, she served as senior assistant parliamentarian for a decade. Her experience includes advising on key legislative moments such as the passage of President Biden’s Inflation Reduction Act in 2022, the COVID-19 relief package, and even assisting Chief Justice John Roberts during the impeachment trials of former President Donald Trump.
At the core of her current task is the Byrd Rule, a set of guidelines that governs what can be included in budget reconciliation bills—bills that can pass the Senate with a simple majority, bypassing the 60-vote threshold usually needed to overcome a filibuster. The rule prohibits provisions that are “extraneous” to the federal budget, including those without significant fiscal impact, those merely incidental to broader policy, and any items that affect Social Security or increase the deficit beyond the budget window.
In Senate circles, the rigorous review process is often referred to informally as the “Byrd Bath.”
This process has had significant consequences in the past. During negotiations over the Democrat-backed Build Back Better plan in 2022, MacDonough struck out immigration provisions that did not pass the Byrd Rule test—forcing Democrats to drop those elements to maintain the reconciliation pathway.
Now, as lawmakers consider President Trump’s expansive budget package, several contested provisions may be subject to similar scrutiny. Democrats are preparing for a robust challenge to elements they believe violate reconciliation rules.
“In the Senate, our committees have been working overtime to prepare for the Byrd Bath, targeting the litany of policies included in the Republican plan that are in clear violation of the reconciliation rules and in some cases, an assault on our very democracy,” Senate Minority Leader Chuck Schumer wrote in a letter to colleagues Sunday night.
A few elements of the House bill are already flagged as potentially vulnerable:
- AI Regulations: The bill seeks to block state and local governments from enacting any regulation of artificial intelligence systems for a decade.
- Federal Court Restrictions: A new legal hurdle in the bill could limit how litigants challenge the federal government in court. Senator Joni Ernst of Iowa recently expressed skepticism about its eligibility under reconciliation, saying, “I don’t see any argument that could ever be made that this affects mandatory spending or revenues.”
- Planned Parenthood Funding Ban: A measure to deny Medicaid funding to Planned Parenthood over abortion services may also be struck down, as a similar provision was rejected by the parliamentarian in 2017.
The full impact of MacDonough’s rulings remains to be seen, but as the Senate enters this decisive phase, her decisions will carry significant weight in shaping the final contours of the legislation.
