A LATE push by trade unions in the Scottish Labour leadership race could hand victory to Richard Leonard, his rival’s campaign has admitted.

Sources close to Anas Sarwar, the millionaire centrist MSP, had grown increasingly hopeful of winning in recent weeks.

However a concerted effort by trade unions to persuade affiliated supporters to back Mr Leonard, a former GMB official, appeared to be shifting the odds in his favour.

“We could still win,” said one supporter of Mr Sarwar, “but Unite have really put their foot down in the past week. It’s going to come down to a few hundred votes.”

After one of the messiest and most divisive political scraps in recent years, the ninth leader of Scottish Labour since devolution will be declared in Glasgow on Saturday morning.

One of their first tasks will be to try to unite a party which has been bitterly split since Kezia Dugdale quit as leader last August after just two years in the post.

They will also have to cope with a sleaze scandal involving former interim leader Alex Rowley, who stepped down on Wednesday and was suspended from the party at Holyrood.

An email sent out by Mr Leonard’s team revealed his campaign had spent £10,000 in the last week alone. He encouraged supporters to donate £20 or more to pay for the spending.

Seen as the left-wing candidate, Mr Leonard has the support of the majority of trade unions – while Mr Sarwar is backed by key party figures such as MP Ian Murray and current interim leader Jackie Baillie.

Speaking ahead of the result, Mr Sarwar said he was “immensely proud of leading a positive campaign, which put forward new, radical, bold policy ideas”.

He added: “Our campaign to put Labour values at the heart of Scotland’s future galvanised and motivated thousands who want our party to fight harder against a Tory Brexit, be bolder in our ambition to lift children out of poverty, and be more radical with tax powers.

“If elected leader, I will work tirelessly to return us to power so that Scotland has a government that works for the many, not the few.”

A source close to Mr Sarwar described the leadership race as “too close to call”.

They added: “There’s been a bit of a late push from the unions to try and increase turnout. That’s key.

“It will have some impact, but it does smack of last minute desperation. The Leonard campaign have been really spooked. I think they thought they’d walk it.”

Glasgow MSP and party health spokesman Mr Sarwar came under close scrutiny early on in the leadership contest for the working practices at his family's firm, as well as his decision to send his children to private school.

Meanwhile, supporters of both candidates raised concerns over the sign-up process for those eligible to vote, with accusations of unfair tactics on both sides.

Saturday's announcement comes just days after the shock suspension of former interim leader Alex Rowley, who was accused of harassing a former partner. He denies the allegations.

It is expected a new contest for the deputy leadership of the party – featuring an all-female candidate list – will kick off if Mr Rowley does not return.

Mr Leonard said his was a campaign “rooted in Labour values from the grassroots up”, which had “shifted the debate in Scottish Labour for good”.

He added: “Now is the time for the Party to come together to take the fight to the SNP and the Tories, for all of those people in all of those communities who need Labour back in power."