JEREMY CORBYN is on course to claim a second Labour leadership victory — and could emerge with an even bigger mandate, his team predicted yesterday.

A spokesman for the Labour leader said he is not taking victory over Owen Smith for granted but believes the evidence shows support for Mr Corbyn within the party has grown since he won with a landslide 59.5 per cent of the vote last summer.

Speaking ahead of his campaign launch today, he said that Mr Corbyn “is not complacent in any way.

“He was elected with a landslide a year ago. By a lot of measures his support has increased among Labour Party members and activists and supporters. And I think there is every reason to think he will be re-elected.”

The 48-hour window to sign up as a registered supporter and vote in the contest for a fee of £25 — up from £3 last summer — closed at 5pm yesterday.

Labour was set last night to reveal the number of people who had signed up, but the total was “already in the tens of thousands” and expected to “accelerate” as the deadline approached.

The secretive Saving Labour group, which has not declared who is leading it or how it is funded, has taken out full-page ads in national newspapers in its campaign to recruit anti-Corbyn voters.

But the party source said: “I think it will be reasonable to assume the majority of them are supporters of Jeremy Corbyn.”

A Times poll this week found support for Mr Corbyn among Labour members had increased by 4 percentage points since the Westminster Palace coup against his leadership began.

It suggested that he would beat Mr Smith by 56-34.

Mr Smith claims to be a “credible and radical” alternative to Mr Corbyn, and has said he would rewrite clause four of Labour’s constitution — stripped of socialist content by Tony Blair — to “put tackling inequality right at the heart of everything we do.”

But the Pontypridd MP has faced yet more questions about his past as an £80,000-a-year lobbyist for trans­national drugs giant Pfizer.

Mr Smith insisted yesterday that he has “never advocated privatisation of the NHS” — a claim at odds with what he told the South Wales Echo in 2006, in which he said privateers could bring “good ideas” and “valuable services” to the NHS.

“Broadly speaking, we made a mistake, the last Labour government, in not appreciating how a Tory government would ride a coach and horses through the language,” he told BBC Radio 4.

“In employing words like ‘choice’ I think we allowed them to use that as a Trojan horse to try and marketise the NHS. I’m opposed to that.”

Mr Corbyn’s spokesman told the Star: “The question of where Owen Smith stands is one open to debate. I’m sure that will  be discussed in the campaign.”

Asked by another journalist whether Mr Smith was more left-wing than Mr Corbyn, the spokesman replied: “Owen Smith? You’ve floored me there.

“I’m sure during this campaign there will be plenty of scrutiny of Owen and Jeremy’s political records and their positions now.”

Mr Corbyn will formally set out his platform in central London this morning.

His campaign website jeremyforlabour.com, launched yesterday, hails victories in the London and Bristol mayoral elections and parliamentary by-elections as proof of Mr Corbyn’s electability.

It also notes how, under Mr Corbyn’s leadership, Labour has overturned Tory plans to cut tax credits and disability benefits and has grown the party to over half a million members.

“He’s only just getting started, and has kept going in the face of huge pressure,” it states.