In an impasse American elections where anything is now possible, there is a potential outcome that is truly the nightmare scenario. What if there is a tie?

As the world prepares to watch the results on election night, the next president of the United States will be the candidate who receives 270 votes in the electoral collegethe process enshrined in the country’s constitution to determine the ultimate winner of the race.

The math is pretty simple: there are 538 members of the electoral college, with each state having the same number of “electors” as the number of seats it has in Congress. To win a majority, either Kamala Harris or Donald Trump must secure more than half of the Electoral College votes, meaning the support of 270 electors, which is why the presidential election is often described as the “race to 270”.

But, 538 is an even number, so it’s mathematically possible that neither Harris nor Trump will reach that goal. In the kind of close elections we’re seeing in the polls, there’s a possibility that the two candidates will split the electoral college right down the middle.

The result of the race that no one wants to contemplate is 269 vs 269.

Although unlikely given the many paths each candidate has to 270, deadlock in the electoral college has occurred once before. In 1800, Thomas Jefferson and his rivals John Adams and Aaron Burr found their race tied, but that was early America, when there were only 16 states and no popular vote to choose the country’s president.

The constitution then, and now, has provisions to deal with an equal vote in the electoral college. But the process takes weeks to accomplish, and the nation would need patience, a commodity currently in short supply.

The outcome of the presidential race would be decided in the newly elected House of Representatives. (Remember, the entire House and a third of the Senate are also up for grabs next week). In January, the members of the new Chamber would be sworn in, and then, as the first order of business, the legislature would elect the new president.

But the process does not give each House member a direct vote. Instead, each of America’s 50 state-level congressional delegations receives only one vote, regardless of the size of the delegation. In that scenario, Harris or Trump would need to win the support of 26 states in the House to secure the keys to the Oval Office. Wyoming (population: 576,851) would have exactly the same weight in this process as California (population: 39,538,223).

The House of Representatives, however, will only elect the president. A parallel process will take place in the new Senate to elect the vice president. There, each of the 100 senators secures one direct vote, so either Tim Walz or JD Vance would need 51 votes to come within striking distance of the presidency.

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In other words, there are circumstances where the president and vice president could come from different parties. Trump could be cheating on Walz. Harris could find himself working alongside Vance.

There are even more tantalizing possibilities that would deepen the nation’s governance crisis.

The House of Representatives could be deadlocked on electing a speaker because with 50 state delegates, a 25/25 split is possible. Members should then continue to vote in an effort to break the tie. If this proves impossible by January 20 – inauguration day – the new vice president elected by the Senate becomes the country’s temporary leader.

Of course, the Senate could also be deadlocked on the vice president because, again, with 100 members, a fifty-fifty split is possible. If that happens, the Speaker of the House would become the nation’s interim president. Currently, that would put Speaker Mike Johnson to the White House, but there is no guarantee that Republicans will either maintain their slim majority in next week’s congressional elections, or that they will keep Johnson as speaker even if they do.

A 269 vs 269 electoral college result would leave the US in limbo for months and plunge Washington into its deepest governance crisis it has ever faced.

It’s statistically unlikely, but in such a close election, it’s an outcome that can’t be ruled out.