How is the House speaker chosen? The Constitution doesn’t say.

The start of a new Congress is always accompanied by anticipation about what laws, alliances and political skirmishes will take shape in the new legislative session. This year, there is also an unusually high level of drama over the most basic question facing the House: Who will serve as speaker?

House Minority Leader Kevin McCarthy (R-Calif.) is vying for the job but has struggled to gain support from enough fellow Republicans, especially hard-right members aligned with former president Donald Trump who see McCarthy as insufficiently supportive of their movement.

If he ultimately doesn’t have the votes to wield the gavel, what happens? Good question, academics say — and anyone looking to the Constitution for guidance will be sorely disappointed.

“The Constitution says almost nothing about the selection process for the speaker of the House,” said Matthew Green, a professor of political science at the Catholic University of America. “All it says in Article One … is ‘The House shall choose their speaker.’ That’s it.”

The role of speaker is one of the few that appears in America’s foundational document. But the rules for picking one — and the powers of the office — were intentionally left vague, the only major condition being that the entire House must participate. Instead, the rules have evolved over centuries. Like other political customs that developed as norms rather than originating from written rules, they’re more vulnerable to possible abuse or dysfunction.

By tradition, the speaker is selected by a roll-call vote in which a majority is required to elect a speaker, though in theory if some members vote “present,” a nominee can still win a plurality of the votes cast and become speaker. In Congress’s early years, the speaker vote was done by secret ballot, which made coalescing around any candidate difficult, leading to consistent gridlock in the country’s first decades.

“The earliest parties formed in part around electing the speaker,” said Eric Schickler, a professor of political science at the University of California, Berkeley. “In the second and third Congresses, there were more Jeffersonians elected, but the Federalists were organized” and elected their choice of speaker. “That started this practice of parties getting together and trying to settle on one candidate at the start,” Schickler said.

The new Congress is set to gather Tuesday to elect a speaker and enact the rules for the new Congress, two things that must happen before they can do anything else.

A majority of the chamber, 218 votes, is usually needed to be elected speaker. Both parties traditionally nominate their caucus leader for the job; if the majority leader’s party rallies behind him or her — a scenario which McCarthy’s allies hope for as he stands more than five votes shy of the needed number — the roll-call vote is completed in a single round. The speaker roll-call vote is overseen by the incumbent clerk of the House, an administrative role that records the happenings of the chamber.

If no nominee commands a majority of the chamber, the clerk can conduct a roll call until a victor is decided, or they can amend the rules to force out the least popular candidates or allow for only a plurality to elect the speaker, as was sometimes the case in the 1850s. The 1856 fight for speaker took two months, the longest in history, and was only resolved with a plurality vote.

The House can still vote to adopt the rules for the new Congress without electing a speaker, but until a speaker is selected, there are no other official members of the House because selecting the speaker is the first order of business to officially constitute the chamber.

As a result, no work can be done until the speaker vote is handled.

In 1859, on the eve of the Civil War, the House was so divided it couldn’t select a speaker for weeks as proslavery lawmakers paralyzed the chamber by tanking the nominations of abolitionists.

In 1923, the House held nine votes for speaker over three days because the House Republicans’ minority Progressive Caucus refused to back the incumbent Republican speaker until he conceded to certain demands, including a seat for the caucus on the House Rules Committee. It was the last time multiple roll calls were necessary to choose a speaker.

“The danger there is that McCarthy gives away the store if he gets elected speaker, it would be a hollow victory because he wouldn’t have the tools he needs to enforce discipline,” Green said.

But there is no rule — and no constitutional recourse — for a situation in which no nominee can garner a majority of the chamber’s support. Instead, would-be speakers must bargain and build relationships to solve any deadlock, which can become easier when the political camps are more sorted.

The power of the speaker has historically closely tracked with the broader state of the nation’s politics. In eras when the major political parties are highly polarized and closely divided in the House, the speaker inversely wields more power. But when the parties were internally divided, the speaker commanded less loyalty from their splintered faction and thus less power in the chamber.

In the Antebellum era, division over slavery created regional fissures within the Democratic and Whig parties and caused “prolonged fights to elect the speaker, where no candidate can get can get a majority,” Schickler said. This happened again between the 1930s and 1970s, when the Democratic and Republican parties were internally split over civil rights and segregation.

“Since the 1970s — accelerating in the 1990s — the speaker has become much more powerful as a party leader,” said Julian E. Zelizer, a professor of political history at Princeton University. “What eras of polarization bring are parties that remain united, which means that the head of the party will have more ease in keeping the caucus disciplined.”

There is another option, which has never been used: House members could elect someone from outside the chamber.

The Constitution is blind to the existence of parties, and any person, whether they are a member of the House or not, can be nominated and become House speaker.

Some members of Congress have signaled that they’re open to a break from tradition in electing a member from outside the chamber who’d have broader, potentially bipartisan appeal. It’s unclear whether such a move would alleviate or inflame tensions in the House.

Lawmakers have become more accustomed to breaking norms in pursuit of policy goals or preserving basic governance. Over the past decade in Congress, they have weakened norms around the confirmation of federal judges and executive branch officials, increased the use of the filibuster, reduced the power of committees and used sweeping spending bills to push through legislation.

Disgruntled Republican lawmakers have another option, Green said: They could vote for McCarthy but then stall Congress by voting against the House rules that are adopted at the start of each two-year session.

Lawmakers’ search for ways to express dissent underscores another dynamic beyond the largely unwritten rules for running Congress; the divides among the new crop of Republicans over strategy will be a challenge for whoever becomes the next speaker.

“It’s an odd situation where, on the one hand, due to polarization, you’d expect Republicans to have a strong speakership. But instead you have a faction within the party who, pretty much no matter who is nominated, they’re going to be causing trouble for that person,” Schickler said.

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