What happens to the 73 seats currently occupied by Brits in the European Parliament once the U.K. leaves the EU?

That's the question confronting European lawmakers who discussed it Tuesday during an “exchange of views.”

Ideas floated for the future allocation of seats have ranged from the practical plan of simply scrapping the seats to the Euro-utopian proposal of creating a pan-European list.

Gianni Pittella, the president of the Progressive Alliance of Socialists and Democrats group, said he had "sympathy" for the idea of a pan-European list, "which would represent a step forward in the process of integration and creation of a European democratic space,” he said.

Another promoter of the pan-European plan is Emmanuel Macron, the centrist candidate who is favorite to become France’s next president, who incorporated the idea in his presidential program.

But others are not so sure. Critics charge that a pan-European list — allowing candidates to represent a single European constituency — is an unrealistic and federalist whim that would require a treaty change. They believe these lists would further deepen the existing gap between EU citizens and politicians.

Alongside Italy, the Brits' 73 seats make up the third-largest delegation in the Parliament.

“Electing MEPs without roots, without any marked out territory, would be contrary to our efforts to get citizens closer to European lawmakers,” said Constance Le Grip, a member of the European People's Party, who hails from France.

Paulo Rangel, a member of the EPP from Portugal, said these lists would "create more Eurocracy" at a time when "the mood is not very pro-European."

For now, British MEPs have the right to keep their seats until Britain exits the union. If the Brexit timeline holds, these MEPs will step down a few months before 2019 European elections.

Alongside Italy, the Brits' 73 seats make up the third-largest delegation in the Parliament and a substantial bloc of mainly right-wing and pro-Brexit lawmakers.

Historical roots

The idea of a pan-European list first emerged in a 2011 report drafted by former liberal MEP Andrew Duff, who proposed that an additional 25 MEPs be elected by a single constituency “formed of the whole territory of the European Union.” His proposal was approved in the Constitutional Affairs Committee at the time but MEPs deemed it too integrationist and it was never adopted.

Though European political parties may be little-known in European capitals, they "contribute to forming European political awareness," as a 2015 report drafted by Polish MEP Danuta Hübner and German MEP Jo Leinen put it.

The report, which proposed the creation of a “joint constituency” to elect the European Commission president, in which “lists are headed by each political family’s candidate,” argued that European parties should play a more significant role in Parliament elections “to show the link between a vote for a particular national party and the impact it has on the size of a European political group in the European Parliament.”

Former MEP Daniel Cohn-Bendit, told POLITICO last year that he supported such an idea. “We would take the 73 seats left vacant by the Brits and put these seats at the disposal of transnational, trans-European ballots.”

Some are more equal than others

But some also argue that pan-European lists would reduce inequality in a parliament where large countries have few MEPs while small countries are overrepresented.

European political parties "contribute to forming European political awareness" — 2015 parliamentary report

An alternative would be to drop the 73 British seats — the simplest, most cost-saving alternative but one that may, in fact, worsen the current imbalance. “The number of seats per country would remain unaltered, which may be politically the easiest solution,” a recent report published by the Bruegel think tank said. “However, this would increase the inequality of representation in the European Parliament.”

A third option would be to distribute the seats among the remaining countries while sticking to a national maximum of 96. But that could be even worse. "This would dramatically increase the inequality of representation," the Bruegel report said.

Brexit notwithstanding, the European Council has asked Parliament for proposals for new ways to allocate seats among countries. The Council will then choose the best option before Parliament ultimately signs off on it.

Math geniuses with an interest in constitutional affairs should let Parliament know.