And so it is confirmed.
After Super Tuesday, it seems clear that the presidential election of 2024 will be a rematch—the first time a former president has challenged a sitting one since 1912.
The candidates are exceptionally well-known, yet about 12% of voters have yet to choose between them. Those swing voters may decide what is shaping up to be a tight race.
In the six elections before the year 2000, the average margin of victory in the popular vote was nine points. In the six since 2000 it has been three points.
Even that understates how close presidential elections are these days. Just six states will be competitive in November.
Last time, around 160 million Americans voted, but Joe Biden won Wisconsin, the tipping-point state, by 20,000 votes, or 0.013% of the total votes cast. When elections are this close, small differences in the inputs can have world-changing effects.
Because of this, any one of a dozen things could tip the election to President Biden or Donald Trump. There are the issues: the economy, the border, abortion. There are the turnout and persuasion operations, the donors and the volunteers.
But in this election there are also three other big areas of uncertainty.
Read more: Robert F. Kennedy Jr: A controversial figure with a ‘cursed’ family history
Role of third parties
The first is the role of third parties. Many Americans find both main parties a bit weird. In theory, breaking their duopoly would be wonderful. In practice, a glance at the existing third-party candidates is a cure for that line of thinking.
This year’s crop includes Jill Stein, an environmentalist whose singular contribution to America may have been to ease Mr Trump’s victory in 2016 and his withdrawal from the Paris climate agreement.
It includes Cornel West, a left-wing professor who thinks there is not much difference between Mr Biden and Mr Trump. And then there is Robert Kennedy junior.
The two big parties jealously guard their duopoly. Since 2000, when Ralph Nader took enough votes in Florida to tip that state for George W. Bush, the parties have tightened the rules around who can get on the ballot for a presidential election.
Ms Stein and Mr West are unlikely to qualify in every state (though they could still hurt Mr Biden). Mr Kennedy is different. In polls that include third parties, he gets 12% of the vote.
That suggests he ought to get enough signatures to put him on the ballot in most states. And if those polls translated into vote share in November, it would be by far the highest third-party score since Ross Perot in 1992.
It is hard to be precise about whom Mr Kennedy would draw more votes from. The surname suggests he would attract more Democrats, yet Republicans like him more.
His environmentalism and vaccine-scepticism mix issues of left and right. His cheerleaders are Silicon Valley bros who think disruption is an intrinsic good. All of which means that a scenario in which Mr Kennedy helps Mr Trump to victory is disturbingly possible.