HARTLEPOOL, England — It used to be simple in Hartlepool.

Come election time, a majority of voters in this coastal working class town in the northeast of England would inevitably back the left-leaning Labour Party. Proud of its industrial history as a center for shipbuilding — the H.M.S. Trincomalee, Europe’s oldest floating warship, sits in the town’s windswept marina — this is still regarded a Labour heartland as the United Kingdom prepares for an election Dec. 12.

But old ties are being tested to their limits with a possibly devastating impact on Labour, which is fighting to defeat the ruling Conservative Party. Voters in Hartlepool feel they have missed out on the economic growth of the last few decades, which has transformed London and the southeast of England. This is the eastern edge of what pollsters have called the “red wall” of Brexit-supporting seats Labour holds with a majority of less than 8,000 votes.

And there’s another problem facing many traditional Labour voters here: the party’s leader, Jeremy Corbyn.

“I don’t think he’s a good leader,” said Christine Scott, 57, as she prepared some herring for sale in Hodgson’s fishmongers, part of a family-owned business that’s been in Hartlepool for more than a century. “I’m not 100 percent sure about him.”

Fishmonger Christine Short works in her shop in Hartlepool. Ian Forsyth / for NBC News

Scott agrees with Labour’s sweeping proposals to nationalize key companies or sectors, such as the Royal Mail and water and rail companies, and its staunch defense of the country’s National Health Service, which many believe the ruling Conservatives are seeking to privatize.

But Corbyn is going too far, she feels.

“He’s making promises that are going to push us further and further into debt,” she said. “And if we come out of Europe, can we actually afford it?”

Without any prompting, Corbyn, a self-described socialist who spent most of his career on the far-left fringes of the party, is repeatedly brought up by voters, many of whom see him as too radical or too detached from the realities of daily life.

The people of Hartlepool are not alone: An Ipsos/MORI poll in September found Corbyn to be the least popular opposition leader of the last 45 years with a net satisfaction rating of minus 60. Corbyn’s rating has improved to minus 35 during the campaign but he remains divisive, including among Labour voters (the same survey has Boris Johnson on minus 14.)

Corbyn’s unpopularity, as well as the party’s perceived zig-zagging on Brexit, are eroding the party’s chances not only in Hartlepool but also other similar seats from northeast England, through the Midlands, the Northwest and into Wales.

Hartlepool marina. Ian Forsyth / for NBC News

A YouGov poll released last week and based on more than 100,000 interviews with voters across the country predicted a Conservative win on a comfortable vote share of 43 percent, with several iconic Labour seats under threat.

In just the seats surrounding Hartlepool, Stockton-on-Tees is predicted to be only a very slim Labour victory; Sedgefield, former Labour Prime Minister Tony Blair’s seat, is too close to call, while Bishop Auckland, held by Labour for all but four years since 1918, and Darlington, Labour since 1992, are predicted to be Conservative wins.

Further afield, in Bolsover in Derbyshire, the veteran 87-year-old Denis Skinner — nicknamed the “Beast of Bolsover” for his fiery speeches — has been the member of Parliament for almost 50 years. According to YouGov, he too faces defeat.

Hartlepool is described as a “likely” Labour win, but at the upper range of Conservative vote predictions so with a especially low turnout for Labour supporters, an upset is still possible.

Hartlepool is seen as so vulnerable for Labour that the upstart Brexit party — formed by U.K. Independence Party founder Nigel Farage as a right-wing, populist challenge to the “Westminster elite” it accuses of trying to stop Brexit — has nominated its chairman, Richard Tice, to stand there. The hope is he can convince traditional Labour voters to change sides.

The pilots building at Hartlepool headland Ian Forsyth / for NBC News

Meanwhile, the ruling Conservative party is similarly hoping its simple slogan “Get Brexit Done” will win votes on its own.

Labour’s manifesto — a list of policies British political parties publish before every election — is perhaps the most radical plan since the party’s post-World War II policies that helped transform and rebuild the country’s economy. It promises a wholesale change in the relationship between the state and the private sector, and poses a long list of benefits and spending promises totaling more than 83 billion pounds ($106 billion). Among the pledges is to provide free high-speed broadband to every home and business and to scrap university tuition fees entirely.

These sorts of promises are supposed to resonate in a place like Hartlepool, where 1 in 4 people are economically deprived, one-and-a-half times the national average. The average life expectancy for men here, according to the Office for National Statistics, is 76.1 years -- a year lower than in 2010. In Kensington and Chelsea in central London, men can expect to live to 83.2 years on average.

Many shops, pubs and nightclubs are boarded up and derelict, and 35 percent of people are out of work — the second highest rate in the U.K.

But despite these disadvantages, Labour’s promises do not always hit home here.

“I’ve voted Labour all my life. [But it’s] false promises all the time, all the things he’s saying he can do,” John Potts, 68, said referring to Corbyn.

“Broadband? Woah, man, the hospitals have got no nurses, no doctors, and we’re getting broadband? I was like, ‘God help us.’”

Amy Heald, 19, from Thornaby is a student in Hartlepool. Ian Forsyth / for NBC News

Pott is a lifelong Labour voter who voted to leave the European Union in 2016, but also doesn’t like Corbyn, doesn’t trust the Conservatives and thinks the Liberal Democrats — who have promised to stop Brexit if elected — are anti-democratic.

Pott said he would be happy for the sitting M.P., Labour’s Mike Hill, to keep his job, but with a lower majority. Labour’s core constituents are happy to see the party win, but while sending a message of protest.

“He’s got a safe seat, he’ll win the seat. What I want to try and say is, ‘We’re not happy with your performance, we want you to do better for us.’”

Corbyn’s supporters have hailed the strength of support among younger voters. Amy Heald, 19, studying art history, is impressed with the party’s policies but still remains unsure.

“I’m a bit scared to vote, because everyone will just go, ‘Why did you vote them?’” she said.

And what could hamper Labour’s chances further is a feeling of hopelessness.

Ray Smedley from Hartlepool. Ian Forsyth / for NBC News

Ray Smedley, 57, retired for medical reasons and can no longer work. A former Labour voter, he said he’s decided to sit out this election.

“I worked all my life, I got retirement through medical health and I can’t claim a penny because she’s working,” he said, gesturing to his wife, Louise. “So nobody’s helping me out whatsoever. Nobody’s interested. There’s people who haven’t worked and are getting all sorts.

“You don’t want either of them to win really. At the minute, I wouldn’t vote and I can’t see me changing my mind.”

Pent-up frustration

Mike Hill, who has represented Hartlepool Parliament since 2017, is not fazed by the cold dark nights of campaigning that await him on the campaign trail. The Northeast is known for many things, but warm weather isn’t one of them.

Traditionally held in May, this is the first general election to be held in December since 1923, reflecting the government’s desperation to win a renewed mandate and a parliamentary majority to get its Brexit withdrawal deal, already agreed by the E.U., passed.

“We’re used to it. You just wrap up warm and put a few more layers on and get out there,” Hill said in the local constituency office, surrounded by leaflets and guides for volunteers for each area of the town.

Hill underlined that Brexit is not the issue that most frequently comes up on voters’ doorsteps.

“It’s all about things that affect people’s daily lives, so people are talking to us about unemployment, the NHS, pensions, TV licences, education, council tax, state of the roads, crime, all of the things that affect them,” he said.

But does he accept that people are angry here?

“I would swap the word anger for frustration. There’s a lot of pent-up frustration, and you can’t blame people, who really are fed up of Brexit, which is why it’s important to hear all the other issues coming through. ”People are fed up, and I share that frustration, as the former M.P. It has gone on for far too long.”

Hill won 52 percent of the votes cast in 2017 and has a majority of 7,000 votes.

It’s not going to be easy to win by this margin again. The Brexit Party chose Hartlepool to launch its election campaign, and paid for billboard trucks to trundle through town bearing a simple message: “VOTE BREXIT, STOP CORBYN.”

Mike Hill, Labour Party parliamentary candidate for Hartlepool. Ian Forsyth / for NBC News

“I have as much of a fight on my hands as I did in 2017 when the Conservatives came second and in 2017 when UKIP stood and came second,” Hill said, referring to the precursor of the Brexit Party founded by Farage.

Has this been an issue on the campaign trail? Hill briefly pauses to think.

“Jeremy Corbyn’s name has come up on the doorstep. We also have had conversations about him being a passionate leader and a guy who wants to make things work and happen for the country for the benefit of all citizens,” he said.

“I wouldn’t say he is the dominant factor on the doorstep, but the focus in my mind will be on our manifesto pledges and I’m confident people will take to them and warm to them.”

Not everyone in Hartlepool supports Brexit. One of the 14,000 people here who voted to stay in the E.U. is Anne Flounders, 67, who like so many others doesn’t know how to vote in this election. She’s considering the Liberal Democrats, the centrist anti-Brexit party that from a strong start has hemorrhaged support after pledging to cancel Brexit if it was elected and is now projected to win 14 percent of the vote.

“I won’t vote Labour while Jeremy Corbyn’s the leader,” she said, emphatically.

“I’ve said that from the day he got in. Obviously I wouldn’t vote Tory because of Boris Johnson — there are not enough words to describe him,” she said, referring to the leader of the Conservatives and the current prime minister.

“I’m considering the Lib Dems, but who would vote for them after the student fees thing? It’s not really who I want to vote for,” she said, referring to a broken promise made at the 2010 general election to abolish university fees.

A woman walks past a food bank in Hartlepool. Ian Forsyth / for NBC News

Andy Hagon, the Liberal Democrat candidate in Hartlepool, won just 746 votes in 2017, a paltry 1.8 percent of the vote. He is hoping for an increased vote share based on frustration with the Brexit process and the fact he is the only pro-remain candidate.

“If we go into a recession, Hartlepool is one of the poor neighbours in the northeast and the Tees Valley and tends to have higher poverty than other places,” he said.

“And I can’t blame people: if they feel things can’t get any worse, you do want a change. But we’re blaming the wrong people.”