Votes are being counted in the Hartlepool by-election with Labour fearing Boris Johnson’s Tories will demolish another brick in the “red wall”.

Ballots were cast across England, Scotland and Wales on Super Thursday in the largest test of political opinion outside a general election.

Results from the Holyrood election – where the issue of Scottish independence was a main feature in the campaign – will come through later on Friday and Saturday.

Before then, the Hartlepool parliamentary contest will give one of the first indications of whether Labour leader Sir Keir Starmer has been able to turn around his party’s fortunes in its former northern heartlands.

Bookmakers have made Tory Jill Mortimer favourite to take the seat in a rare by-election victory for a governing party, with a result expected shortly before dawn on Friday.

A Labour source said: “These were always going to be tough elections for Labour.

“Keir has always been honest about the mountain we must climb to rebuild trust to win the next general election.

“Labour is listening and we will continue to change in order to win back the trust of working people in Britain and their communities.”

Shadow cabinet minister Thangam Debbonaire admitted the party’s message had not been cutting through.

“We’ve got a great team who cannot wait to be able to cut through more and I hear what people are saying, it’s not cutting through, I get that,” she told BBC’s Question Time.

“I think that’s a lesson for the Labour Party that we’re going to have to take into account.”

Hartlepool held by Labour with a majority of 3,595 in 2019, even as other bricks in the red wall crumbled – in part due to the Brexit Party splitting the Tory vote.

Both Mr Johnson and Sir Keir made three visits during the campaign in a sign of the importance the by-election represents to their parties.

The Tories also sought to play down expectations, with one source saying it was “looking tough in Hartlepool” as “Labour have flooded the area with activists”.

But the Conservatives hope to achieve a “hat trick” of successes, winning Hartlepool and retaining the mayoralties in Tees Valley and the West Midlands.

Communities Secretary Robert Jenrick told BBC’s Newsnight: “At this point in previous electoral cycles under Tony Blair or under Margaret Thatcher the opposition would be winning many, many council seats, would be winning places like the West Midlands, like the Tees Valley – in fact it was surprising to many people that we won the Tees Valley in the first place four years ago.

“Seats like Hartlepool which Labour have held for 40 or 50 years, it would be inconceivable that the party of government could even be talking about being competitive in those places.”

He told Sky News that “if it is even close, I would say that is a really serious indictment of Keir Starmer”.

Over the coming days results elsewhere could have an even more dramatic influence on the state of the nation’s politics.

Scottish National Party leader Nicola Sturgeon’s push for a second independence referendum means the stakes are high in the Holyrood contest, with results expected to be announced on Friday and Saturday.

The SNP is expected to emerge again as the largest party in the Scottish Parliament after the election, but it wants to win an overall majority of MSPs as it pushes for a second independence referendum – something which polls suggest remains in the balance.

Mr Johnson has refused to countenance another referendum, setting up the potential for constitutional fireworks over the coming years if Ms Sturgeon gets the outcome she desires.

The SNP leader insisted her focus would be on tackling coronavirus and rebuilding the economy.

But she said that “when the Covid crisis has passed, we will give the people of Scotland the opportunity to decide if they want the recovery to be in the hands of the likes of Boris Johnson and the austerity-driven Tories, or to put Scotland’s future in Scotland’s hands with independence”.

Mr Jenrick said: “We do not want to see Scotland, or indeed any part of the UK, now embroiled in a highly divisive and distracting constitutional wrangle.”

The referendum was a “once in a generation vote” and “that means if there is ever one in the future, it is not right now when Scotland and the whole United Kingdom should be focused on building back after the pandemic”.

Results of the elections – which also include the Welsh Parliament, police and crime commissioners and English local authorities and mayors – are expected to continue filtering through until Monday as counting will take longer than normal due to coronavirus restrictions.

In Wales, Mark Drakeford hopes to maintain Labour’s grip on the Senedd – but he may find himself forced to forge a new coalition to stay as First Minister.

That could mean talks with Plaid Cymru, whose leader Adam Price has committed to an independence referendum within five years if his party wins a majority.