The new Scottish Secretary has said Labour can “disprove the critics and cynics” by bouncing back ahead of next year’s Holyrood election.

Douglas Alexander was added to the cabinet as part of a major reshuffle prompted by the resignation of Angela Rayner as deputy prime minister.

The party is trailing in the polls north and south of the border, but Mr Alexander told BBC Scotland’s Sunday Show it could fight back with “hard work, humility and listening to people”, and accused the SNP-led Scottish government of failing services.

The SNP said the reshuffle showed Westminster was in chaos and that Scotland would be better off independent.

He replaced Murray – Scottish Labour’s longest serving MP and a close ally of the party’s Scottish leader Anas Sarwar.

Late on Saturday night, Edinburgh South MP Murray was appointed as a minister in both the Department of Culture, Media and Sport and the Department for Science, Innovation and Technology.

The surprise move followed criticism of his sacking from senior Labour figures who described his departure as a disgraceful decision and a real loss.

Murray himself had also expressed disappointment.

Speaking on the Sunday Show, Alexander paid tribute to the work carried out by his predecessor.

“We owe him, as the Labour movement in Scotland, an immense debt of gratitude,” he said.

He said he was confident the party could get back support that appeared to have dropped dramatically in recent polls in time for next year’s Holyrood elections.

“We were written off in the Hamilton, Larkhall and Stonehouse by-election with very similar arguments – you were dead in the water before you had begun according to the Scottish media,” he said.

“We will come back in Scotland the way that we came back in Hamilton – by hard work, by humility, by listening to people, doing the work on the ground, making the arguments directly to the public.

“I have a sense that the Scottish people are way more ambitious than the Scottish government today.”

He said the party had to take its case to the Scottish public and disprove the critics.

Douglas Alexander has a shiny new job in the Scotland Office.

But the one he was handed not long beforehand – as co-chair of Scottish Labour’s Holyrood election campaign – is perhaps just as crucial for his future and that of the prime minister.

Imagine a world next May where Labour contrives to lose Wales after 27 years of devolution, and the SNP secures a majority at Holyrood and ramp up pressure for an independence referendum.

That kind of blow might see Sir Keir Starmer going the way of Ian Murray.

So for all the discontent there is in Scottish Labour about the way these changes have happened, activists will know they can’t afford not to rally around now.

But this kind of turmoil makes their job that bit more difficult.

Labour’s whole argument is about governmental failure at Holyrood. Today, it’s the likes of the SNP and Reform UK looking to capitalise on the same message about Westminster.

The SNP MP for Moray West, Nairn and Strathspey, Graham Leadbitter, said Murray had not “exactly set the heather alight” and had not had “any great vision for Scotland”.

“In Douglas Alexander’s past campaigning against independence in the referendum in 2014 he was very negative about Scotland,” he added.

“So I am really not holding out much hope for the future of the Scotland Office in terms of delivering a positive agenda for Scotland.

“In the meantime, the SNP will continue to set out our positive vision for Scotland and highlight the positive record in things that the Scottish government continues to do.”

He said the “nonsense of a government” at Westminster was doing very little for the people of Scotland.

Scottish Conservative deputy leader Rachael Hamilton said Labour was in “complete meltdown” and its integrity was “in tatters”.

“Ian Murray’s sacking was entirely in keeping with the chaos that surrounds Keir Starmer’s shambolic government,” she said.

“The fact Ian Murray has now had to be shoehorned into a junior ministerial role after such backlash is systematic of the weakness of Keir Starmer and his long list of U-turns.

“The uninspiring appointment of Douglas Alexander, who is nothing more than a yes man for Labour, will mean more of the same broken promises.”