Is this going to be the Conservative Party’s David Miliband moment? It looks as if the final two candidates will be Rishi Sunak and Penny Mordaunt, with the main uncertainty in the next few days being the battle for third place between Liz Truss and Kemi Badenoch.

Then it will be up to Conservative members to make the final choice. A YouGov poll of members this week suggested that Mordaunt was preferred to Sunak by a large margin, 67 to 28 per cent, and she is consequently the betting favourite.

The Tories are in danger of rejecting their David Miliband: the well-qualified leader tainted by his association with the old regime. Mordaunt is their Ed: the new face appealing to a party that yearns to be liberated from the constraints of reality.

The Conservatives could be on the brink of making a decision that they will regret for a long time. I was startled when an older former Labour voter in a northern constituency said in a focus group this year that the party had chosen the “wrong brother”. Twelve years on, that road not taken still haunts Labour.

Sunak, like David Miliband, tells his party what it doesn’t want to hear. The voters want a working NHS, good schools, and lots of police officers deterring crime. That cannot be paid for indefinitely out of thin air, or borrowing, as it is usually called. It is no coincidence that David Miliband’s undelivered acceptance speech, published after the wrong brother was elected, was strong on fiscal responsibility: “George Osborne says we are in denial about the deficit. Because he wants us to be. So let’s not be.”

This is not a Blairite argument, although Sunak is plainly the more Blairite of the two Tory candidates, given that they both voted to leave the EU. It is an argument about fiscal and electoral reality. The next election is not going to be won by a Conservative Party promising higher borrowing or public spending cuts. If Mordaunt becomes prime minister, she will not usher in a significantly smaller state than Sunak would, so she will have gained the office on a false prospectus.

After losing one prime minister because he struggled to tell the truth about the hard choices governments have to make, this would be unfortunate. Yet Mordaunt promises an £8bn income-tax cut by raising thresholds in line with inflation, and says she’ll work out how to pay for it when she does a Budget “in the round”. This is not serious politics.

Yet it seems to be what the party members want. We can understand that on the level of mass psychology. Conservative members are confused and exhausted by the after-effects of the coronavirus. Not just the vast public spending to protect people’s jobs, but the illiberal lockdowns. They just want to get back to “the old stuff”, as Mordaunt called it in her campaign launch.

The parallel with the Labour Party in 2010 ought to frighten Sunak. Then, Labour members were confused and exhausted by the compromises they had had to make in 13 years of mostly successful government. They just wanted to get back to the old stuff of “socialism” — never defined — and not having to be responsible the whole time.

All is not lost, not least because the Conservative Party is still in government, which means that some of its members, at least, still want to avoid the indulgence of opposition, leading presumably to the Tory equivalent of Jeremy Corbyn. As well as showing Mordaunt in the lead, the YouGov poll revealed how volatile Tory members are. The company’s previous poll, carried out only six days earlier, showed Mordaunt and Sunak neck and neck. That is why the TV debates and hustings are so important, because Tory members are open to persuasion.

Sunak made a good start in the Channel 4 debate last night, challenging Mordaunt’s fairytales on tax and emerging as much the stronger of the two in post-debate polling. In particular, Sunak was rated as the candidate most likely to win a general election — doing better even than Tom Tugendhat, who was rated best overall but is like Rory Stewart in the 2019 contest, and is still the most likely to be knocked out in Monday’s ballot of MPs.