Exclusive:Douglas Alexander 'remains neutral' in Scottish Labour leadership contest

Mr Alexander, along with junior minister Melanie Ward and Scottish whip Gregor Poynton, are understood to be remaining neutral in the race.

But No10 Downing Street has given all other ministers and Parliamentary Private Secretaries (PPSs) the freedom to endorse who they wish.

A spokesperson for Mr Alexander said: “Scottish Labour Ministers serving in the Scotland Office stand ready to work with whoever is elected as Scottish Labour Leader and will continue to work constructively across the political spectrum in the best interests of the people of Scotland.”

It comes as a second Scotland Office aide backed Joe Fagan in the contest.

Alison Taylor, PPS to Mr Alexander, said Mr Fagan “has demonstrated a capacity to work across political boundaries and get things done”.

She follows her Scotland Office PPS colleague Frank McNally in supporting the former South Lanarkshire Council leader.

Paisley and Renfrewshire North MP Ms Taylor said: “Following the disappointing result in this year’s Scottish Parliament election, it is now time to choose a new leader to take the party forward and lead the Labour group of MSPs.

“Like all Scottish Members of Parliament, I have the opportunity to nominate a candidate, and there are a number of good candidates. I appreciate Monica Lennon’s passion and enthusiasm, Michael Marra’s intelligence and mastery of the economic case for Labour.

“But in this election I’ll be supporting Joe Fagan. Joe has demonstrated a capacity to work across political boundaries and get things done. He led one of Scotland’s largest local authorities in a cross party coalition to deliver real change for his community.

“I believe he will bring that spirit to his leadership of the party in Scotland, building from where we are to achieve consensus across parliament.

“That’s why I will add my name to the list of those nominating Joe Fagan as our next Scottish leader.

“I know that whatever the outcome of the contest, our Scottish Labour team will work together to demonstrate the difference Scottish Labour can make to the lives of people across the country and I look forward to playing my part in that task.”

Ms Taylor is just the fourth MP to back Mr Fagan in the leadership contest.

Some 11 MPs have so far said they are backing Mr Marra, while two are supporting Ms Lennon.

Mr Marra has the endorsements of several ministers, including former Scottish Secretary Ian Murray, Blair McDougall and Martin McCluskey.

Each candidate needs the backing of three MPs, three MSPs and three affiliates, two of which must be trade unions, to reach the ballot.

Although well over a dozen are yet to publicly declare who they are backing, Ms Lennon is understood to be struggling to get the third MP backer she needs.

However, her campaign was boosted yesterday as Unite union prepares to back Ms Lennon in the leadership race.

Each of the candidates need the support of two trade unions to make it onto the ballot.

Ms Lennon is not expected to struggle for union nominations.

A source said: “The meeting of the Unite Regional Labour Party Liaison Committee decided to make a recommendation to the union centrally that it should nominate Monica Lennon in the Scottish Labour Party leadership election.”