If Labour reelects the far-left Jeremy Corbyn as its leader this week, which seems likely, and the Conservatives under Theresa May do lurch a little to the right, that should leave space in the center of British politics for the Liberal Democrats.

Unfortunately for them, that space will never be very wide.

I argued here the other day that May is breaking — however carefully — with David Cameron’s liberal legacy in order to secure the support of suburban and provincial voters who are more right-wing than the party has been. Many of them voted Conservative in 2015 and many voted to leave the European Union in the referendum in June, prompting Cameron, who had advised a “remain” vote, to step down.

A rightward shift under May, on education and immigration policy, could tempt more urban and liberal-minded voters to defect, I warned:

If May seems in thrall to those who voted to leave the EU because they are dissatisfied with the modern world, don’t be surprised if those who only voted for the Conservatives when they had finally come to terms with the modern world abandon her in the future.

Liberal Democrat leader Tim Farron is exploiting this vulnerability. His is now “the free-market, free-trade, pro-business party,” he told a conference in Brighton this week.

“Hole in the center”

Farron simultaneously appealed to Labour moderates who do not share Corbyn’s pacifism nor his far-left economic views, saying there is “more to Tony Blair’s legacy” than the Iraq War (which Corbyn opposed). His center-left government “gave us the national minimum wage,” Farron said. “It gave us working tax credits. It gave us NHS investment and a massive school building program.”

“There is a hole in the center of British politics right now,” according to Farron: “a huge opportunity for a party that will stand up for an open, tolerant and united Britain.”

The only part that’s wrong with that statement is where he said “huge”.

Britain’s electoral system punishes third parties

Even when they won 23 percent of the votes in 2010 — their best performance in three decades — the Liberal Democrats got only 8 percent of the seats in Parliament, or 57 out of 650.

Chris Applegate and Tom Phillips have calculated that even if a single party got the support of those 48 percent of Britons who voted in the referendum to stay in the EU, it would still scrape together no more than 229 seats against 421 for the 52 percent who voted for “Brexit”.

The reason (or problem, if you will) is Britain’s electoral system. Lawmakers aren’t elected nationally but at a constituency level, similar to how congressmen and -women in the United States are elected in districts.

Because those potential Liberal Democrat voters, the 48 percent who voted to remain in the EU, are clustered in Britain’s major cities, they are underrepresented in Parliament.

Just as America’s electoral system gives an advantage to rural districts and states, such as Montana and Wyoming, Britain’s favors lightly-populated constituencies in the English countryside, which is where many of May’s small “c” conservatives live, as well as the more densely-populated postindustrial areas of Liverpool, Manchester and Newcastle, which is where Labour’s working-class base is concentrated.

Short of electoral reform, which the British rejected in another referendum, in 2011, the Liberal Democrats will always be at a disadvantage.