The British Labour Party is enduring what might be called a “GOP moment”. In the bitter battle for the leadership and soul of the party, like the US Republican Party, it is caught on the horns of a dilemma between democratic accountability to its membership and electability.

The members naively believe the party is a vehicle through which they can radically change society, the MPs, that its purpose is to elect them and that a radical programme would be akin to what one MP described the 1983 manifesto, “the longest suicide note in history”.

Ironically, as the 640,000 ballots go out by post this week, the old Blairite leaders and their latter-day clones in the parliamentary party, must be rueing their enthusiastic 1980s’ embrace of one-member:one-vote. Then it was a surefire means to sideline the “unrepresentative” left-wing activists who dominated the party’s general management committees and conference and did much of the organising on the ground.

Concentrating policy formation in the hands of the leadership and vetting candidates to ensure MPs also sang off the same hymnsheets, the party’s leaders sucked the oxygen out of the body of a compliant party whose membership, unsurprisingly, plummeted. Little did they imagine how the tide would turn, and with a vengeance.

Now the anti-establishment politics that have swept Europe and the US have brought a massive influx of idealistic new members into Labour in support of Jeremy Corbyn – 130,000 joined the party in the past six months alone. Although likely to be less clearcut than the landslide which saw him elected last year, Corbyn appears set comfortable to defeat the MPs’ candidate Owen Smith.

Smith, who stands on the left of the party, has sought, with the support of heavyweights like London mayor Sadiq Khan, somewhat unconvincingly to portray the contest as one about competence and electability; not politics.

But the argument, and the implicit threat from allies that they will split from the party if Corbyn wins, do not find an echo among a new rank and file that simply does not trust Smith not do a Blair on them.