The Conservative Party has been teased by electoral reform campaigners, after the previous frontrunner James Cleverly was knocked out of the party leadership ballot, apparently by accident due to tactical voting on Wednesday.
Former party chair Greg Hands called for an overhaul of the party's voting system for leadership elections following the debacle.
It comes after several rounds of voting by Conservative MPs, to pick a final two candidates who'll go to party members in a vote, drew to a chaotic close on Wednesday.
Right-wingers Kemi Badenoch and Robert Jenrick emerged - to the shock of MPs, members and the press - as the last two contenders.
The strange turn of events saw the previous favourite James Cleverly eliminated in the final round of MP voting, reportedly due to a surge of tactical voting by Conservative MPs to knock out whoever they viewed a 'weaker' competitor to Cleverly of the final two being put to members. It backfired spectacularly, if so.
The tactical voting came despite warnings from campaign chair, Grant Shapps, to stick with Cleverly and not to try any 'clever' tactics.
The remaining candidates, both from the right wing of the party, will now campaign to win over Conservative Party members.
Following the shock result, former Conservative Party chairman Greg Hands wrote: "The rules need serious reform. I am not with any of the camps, but it seems tactical voting has taken place on an industrial scale either yesterday, today, or both.
"It pains me to say it, but one STV [Single Transferable Vote] ballot paper - rather than multiple rounds - would probably solve it."
STV would allow all the 'rounds' of voting to be done at once, rather than over multiple days, as currently happens in the Conservative leadership ballots of MPs. The MPs would write candidates' names in order of preference and the final two frontrunners to go to members could be announced almost immediately.
Doug Cowan, from the Electoral Reform Society, wrote that the voting patterns strongly suggested tactical voting: "It was only in this final round that the [centrist vs right-wing] split became much wider, with Badenoch and Jenrick combined getting more than double Cleverly's 37 votes. In the three previous rounds the combined votes for the 'centrist' candidates was always between 54-59 votes."
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Like in a general election, "first past the post means that it is sometimes in your interest to vote for someone who isn't your first choice," he added.
"If you were an MP who wanted Cleverly to win in the final contest among the party members, and you think he had a lead large enough to be able to be able to lose a few votes and still get through, you might be tempted to vote for the candidate you think he stood the best chance against. Or for the candidate who was your second choice to ensure your least favourite didn't win.
"We can't know what happened, but if this is what has happened, they have massively shot themselves in the foot", Cowan added.
The Chief Executive of pro-proportional representation campaign Make Votes Matter, Emma Harrison, told Byline Times: "It is darkly comic that Tory MPs have ended up advocating preferential voting for leadership elections when the last Government denied the rest of us that same choice at mayoral and PCC elections." Harrison was referring to the last Government scrapping the two-preference Supplementary Vote system in favour of First Past the Post."
"If you want to be more charitable, at least Tory MPs unhappy with the current multi-round system are not suggesting First Past the Post in its place. But at the moment, it really is one rule for them and another for everyone else," the electoral reform campaigner added.
The final postal ballot will be sent to Conservative members by the end of next week. Votes must be received by 31 Octob