KEZIA Dugdale has suffered a blow as Scottish Labour leader after her official spokesman resigned ahead of the council and general elections.

David Ross, one of the most senior figures in Dugdale’s team, will leave after June 8th to join transport firm Scotrail on a temporary basis.

An SNP source said: "It must be an absolute headache for Kezia to lose a top adviser on the eve of a general election."

In 2016, Labour came third behind the Tories at a Holyrood poll for the first time since the Parliament was created.

Labour is bracing itself for heavy losses in today’s local government elections, with former strongholds like Glasgow, North Lanarkshire and South Lanarkshire expected to fall to the SNP.

Ms Dugdale is also fighting to save her party’s sole Westminster seat, Edinburgh South, amid a revival from Ruth Davidson’s Tories in the general election campaign.

Party insiders privately fear Scottish Labour will come behind the Tories in both elections, raising questions about Ms Dugdale’s credibility as leader.

It can now be revealed that a top spin doctor in Ms Dugdale's office is moving on at a critical period for the party.

Mr Ross used to work for Labour peer Lord Browne and former Labour MP Tom Greatrex before becoming “head of media” at the pro-UK Better Together campaign during the referendum.

His social media biography describes him as “official spokesman” to Ms Dugdale and states: “I am a senior staff member in the Scottish Labour Party's communications team, reporting directly to the leader.”

However, Mr Ross has opted to join the Scotrail Alliance as temporary head of media, where he will be reunited with former Better Together communications guru Rob Shorthouse.

Mr Shorthouse provided a testimonial for Mr Ross on the latter’s Linkedin profile page:

“David and I worked together for two years on the Better Together campaign. During that time, David proved himself to be a strategic thinker, problem solver and a very talented writer. I would have absolutely no hesitation in recommending David to employers.”

Mr Ross’s move may be seen as ironic, given that Labour has been at the forefront of criticising the rail operator’s performance over the last twelve months.

Labour has blasted the Scotrail Alliance, which includes private company Abellio, over punctuality and overcrowding and called for the railways to be in public hands.

One Labour insider said: “Scottish Labour must be in a bad way if David is chucking it for Scotrail.”

Mr Ross will continue in post throughout the general election, but leave after the campaign ends.

A spokesperson for the Scotrail Alliance said: “David has a tremendous amount of skill and experience of working with the Scottish media. He will be a first class addition to our team.”

Mr Ross said: "Having worked for our movement in Holyrood, Westminster, various constituencies and at Better Together for almost a decade now, I am ready for a new challenge. I have had the privilege of working in Scottish politics during one of the most interesting periods in our history, working for and with people I will always respect and admire. I have delayed my departure to fight the snap General Election campaign."