Most the time, Elizabeth MacDonough’s job is as unglamorous and uncontroversial as any in Congress—tedious even. Since 2012, she has served as parliamentarian of the Senate, which means her role, as outlined on the Senate’s web site, is “to provide expert advice and assistance on questions relating to the meaning and application of that chamber's legislative rules, precedents, and practices.”

Day to day, the work is pretty straightforward. If a member has a nitpicky question about how to handle an arcane motion, he takes it to MacDonough—typically well before an issue reaches the floor so as to avoid looking publicly foolish. Though appointed by leadership, the parliamentarian strives to be nonpartisan, steeped not in politics but in the brain-frying minutiae of the chamber’s history. (The Senate runs according to a relatively small number of “standing rules,” along with a Trump Tower-sized body of precedents.) When the Senate is in session, the parliamentarian sits on the dais at the front of the chamber and, any time a “point of order” is raised about whether proper procedure is being followed, advises the presiding officer on how to proceed—or not. Parliamentarians avoid the media and, in general, strive for professional obscurity.

But every now and again, this anonymous Senate staffer winds up in a position to decide the fate of high-stakes, hot-button legislation. And just like that, she is thrust onto the radar screens, and into the crosshairs, of ideological warriors, big-money interest groups, and other assorted obsessives. The brewing storm over Ryancare—or, if you prefer, Trumpcare-- promises to be one such moment, suggesting that MacDonough should brace for an acute onslaught of crazy.

Here’s the lay of the land: Republicans’ ability to repeal and replace Obamacare requires Senate Leader Mitch McConnell to ram through much of the overhaul via the filibuster-proof path of reconciliation. This means rejiggering whatever bill clears the House to suit at least 50 of his 52 members. It also means convincing MacDonough that the overall plan meets the requirements of the Byrd Rule.

Adopted in 1985, the Byrd Rule aims to keep budget reconciliation from getting bogged down in “extraneous matter” unrelated to deficit reduction.  The rule sets six tests for determining extraneousness. Some are straightforward, such as a provision’s not being allowed to futz with Social Security. Others are highly subjective, most notably that a provision must impact federal “outlays or revenues” in a way that is not “merely incidental to the non-budgetary components of the provision.” Translation: Reconciliation cannot be used to achieve non-fiscal policy aims (for instance, curtailing access to guns or abortion) disguised as deficit reduction.

The “merely incidental” mandate, as you might imagine, leads to much argument, interpretation, and budget trickery. When that happens, who is charged with making the final call on the legislative intent underlying a bill and, by extension, its eligibility for reconciliation? You guessed it: the parliamentarian.

When a hot policy like Ryancare heads toward the Senate, the parliamentarian suddenly becomes the most popular person on the Hill. Emissaries from all sides of the debate descend on her office to lobby for or against provisions in a practice adorably known as “the Byrd bath.”

“If I’m in the minority, I’m going to say that all these provisions right here trigger Byrd Rule points of order,” said James Wallner, who spent many, many hours in the parliamentarian’s office during his 12 years as a Republican Senate aide. The bill’s supporters, meanwhile, work to tinker with—or if necessary trash—certain provisions to suit the parliamentarian.

There are nuances to this dance that members and staff quickly learn, said Wallner, now head of research for the conservative Heritage Foundation. Parliamentarians don’t deal with hypotheticals. (“You have to have text.”) They can get cranky if you pester them about their process. (“If you’re a staffer, the quickest way to frustrate the parliamentarian is to ask for the specific precedents on which they are basing their advice.”) And if the parliamentarian decides a bill has too many extraneous bits, she can deem the whole thing fatally flawed. “She would then say, ‘OK. This bill’s no longer a reconciliation bill,’” explained Wallner. That, needless to say, would be the end of Ryancare.

Particularly with do-or-die legislation, it pays to start strategizing early, said Jim Manley, a former Senate aide to Democratic leadership. “This is war-gamed weeks and or months beforehand. It’s complicated, legalistic stuff, and you want to have your ducks in a row.”

Indeed, from the get-go, some of Ryancare’s elements were tailored to with an eye toward making the plan “Byrdable.” Even so, there remain several, such as the 30 percent surcharge on premiums for people who don’t keep continuous coverage, that conservative critics (including Senator Mike Lee, National AffairsYuval Levin, and health policy analyst Christopher Jacobs) insist do not pass the sniff test. Which means MacDonough is likely to be making some significant—and controversial—calls in coming weeks.

This burden comes with all manner of professional risks. For starters, although largely treated as an independent operator, the parliamentarian serves at the pleasure of Senate leadership. And leaders have been known to fire a parliamentarian who issued advice they didn’t like. In 2001, then-parliamentarian Robert Dove refused to clear parts of the GOP’s budget plan for reconciliation. Out he went, to be replaced by his deputy, Alan Frumin.

It’s not just lawmakers who get upset. With an issue as toxic as health care, outside activists can get downright scary when they disagree with the parliamentarian. Frumin held the post during the original Obamacare debate in 2010. He denied use of reconciliation for the primary legislation. But when he cleared it for a follow-up bill that made budgetary adjustments to the ACA, opponents went berserk, and Frumin started receiving death threats.   

More subtly, for all the time and energy spent wooing the parliamentarian, her approval isn’t binding. MacDonough’s official duty is to offer expert advice on the rules to the Senate’s presiding officer. But the presiding officer has no obligation, beyond tradition, to heed that advice. Either the presiding officer or the Senate president (Vice President Mike Pence) are free to ignore MacDonough and allow whatever provisions they want to roll on through.  

This is the course favored by some Republicans in both the House and Senate. (Senator Ted Cruz, unsurprisingly, loudly opposes deferring to an unelected staffer on such vital matters.) Other Republicans, however, see dissing the parliamentarian as another form of “going nuclear” akin to killing the legislative filibuster. This sort of talk makes institutionalists (among them Senate Majority Leader Mitch McConnell) verrrrry nervous.

Either way, having her recognized authority questioned by an increasing number of lawmakers is hardly a happy development for MacDonough. Neither is being portrayed as a stumbling block to killing the Obamacare—or, alternatively, as a Republican toady looking to snatch health care coverage from 24 million Americans.

Now, maybe MacDonough will catch a break. Maybe Ryancare won’t make it out of the House. Or maybe already anxious Republican Senators will smother it before it comes to the floor. Or maybe Donald Trump will suddenly become a single-payer fan, and this entire debate will go back to square one. These days, nothing is impossible.

Even so, MacDonough should prepare for the possibility that she is about to have her fifteen minutes of fame—which, in a job like hers, can be a giant pain in the backside.