SOUTHAMPTON, England — As students from the University of Southampton zigzagged across campus on a recent cold afternoon, youthful activists with Britain’s main opposition Labour Party intercepted them with cups of tea and a leaflet with detailed instructions on how to register to vote in December’s election.
“Vote for jobs, vote for housing, vote for youth services, vote for the climate,” the campaigners chanted, as students gathered around them to learn more.
Brexit, generally supported by older generations, is seen by many young people as a threat to their ability to travel, study or work abroad, and continues to be one of the most important issues for youth voters, alongside the environment, education and housing, according to an analysis by YouGov, an internet market research firm based in Britain.
Now, as Britain prepares for its most pivotal election in decades on Thursday, Labour is targeting cities with high youth populations, hoping that they will offset losses in traditional Labour strongholds in the north that support Brexit by healthy margins.
The excitement is often palpable among college students, many of them first-time voters who did not have a chance to participate in the 2016 Brexit referendum that has upended their lives.
“This election is the most significant of our time. It will determine our future,” said Harriet Farmer, 19, a student at Southampton University. “Young people are always overlooked, but in this election, we will make ourselves heard. We are engaged, we have registered and we will vote our way out of this mess.”
The intergenerational gap in support between the two main parties was so wide in the 2017 election that YouGov declared that age had replaced class as the dividing line in British politics. Over 60 percent of voters between the ages of 18 and 29 backed the Labour Party in 2017, while 69 percent of voters over the age of 70 backed the Conservative Party.
That divide was driven by opposition both to Brexit and to the government’s decade-long austerity policy. One of the big questions in this election is whether young voters, who tend to be underrepresented in opinion polls, could spring a surprise.
More than 1.5 million people under the age of 34 registered to vote between Oct. 22 and Nov. 19, compared with 1.2 million in the same time frame in 2017, government figures show. An additional 452,000 people under the age of 34 applied to vote on the last day of registration on Nov. 26.
Analysts caution that while the numbers hint at the possibility of an explosive turnout, they could be overstating the potential impact. That’s because students are allowed to register twice, in their hometowns and in their university towns, but must choose a single place to vote.
Despite the surge in youth registration, the percentage of registered young voters, at around two-thirds, remains low compared with the older population. Young people also make up a big percentage of nonvoters: Only between 40 and 50 percent of the population between the ages of 18 and their mid-20s voted in the 2015 and 2017 elections, compared with about 80 percent of voters in their 70s.
When Prime Minister Boris Johnson called a December general election last month, Johnny Maclean, a 19-year-old fashion student, was delighted. Too young to vote in the 2016 European Union referendum, but ardently anti-Brexit, he would finally have his say.
After reading the policy platforms of the main opposition parties, Mr. Maclean concluded that the Labour Party offered the best opportunities for young people.
“They are promising the largest youth investment out of any other major U.K. party,” he said in a recent interview. “They are promising the full scrapping of tuition fees, free bus travel for all under 25s, raise the minimum wage to £10 and mass invest into youth services to reverse and go beyond the one billion cuts in youth services by the Tories.”
While young voters tend to favor the Labour Party, the youth vote shows the same tendency toward fragmentation as the wider British left. Many have shifted to the Liberal Democrats, a more centrist party with an adamantly anti-Brexit stance, and the Greens.
James Sloam, the author of “Youthquake 2017: The Rise of Young Cosmopolitans in Britain,” believes that youth turnout will be high this week. “All the evidence shows that if you vote in your first election it becomes a habit, so young voters from 2017 would be likely to vote again as well as first-time voters,” he said.
Dr. Sloam’s research found that in the aftermath of the global financial crisis in 2008 young people, having borne the brunt of austerity, unemployment and cuts to services, have become more politically engaged.
With so much at stake in the coming election, young people are also opting to vote tactically. The constituency of Southampton Itchen is home to students from two universities — the University of Southampton and Solent University — and many graduates stay on to work in the city, which is a major port.
In 2017, the Conservative candidate, Royston Smith, won by 31 votes, making it a prime target for Labour this time. Many young residents of the city believe the youth vote will swing the seat to Labour.
“I changed my registration from my parent’s house in Hereford to Itchen, just so that we have a bigger chance at knocking the Tories off the bench,” said Imogen Williams, a 24-year-old computer programmer who works in Southampton. “I just want to stop Brexit, and I know that if Labour wins and calls a second referendum people will vote differently, now that they have actual facts about what a monumental disaster Brexit would be for our country.”
Ms. Williams’s sister, Martha, a student at Southampton University, said many of her friends would be voting for the first time and were divided between Labour and the Liberal Democrats.
“Labour is a fantastic party for the youth, but Jeremy Corbyn is a terrible leader and no one can imagine him as prime minister,” she said. “And then we have the Lib Dems who say they will cancel Brexit, but they aren’t going to get a majority, so people are in a pickle and are just choosing to vote tactically instead of idealistically.”
Even though Mr. Corbyn has lost popularity since the last election, following accusations of anti-Semitism and his refusal to take a personal stance on Brexit, youth support for his party appears to be gathering momentum once again.
“The Labour Party policies may appear radical to some,” Dr. Sloam said. “But with the exception of their ambiguous policy on Brexit, they are extremely popular and their campaign seems to be galvanizing young voters.”
While many young people express enthusiasm and even hope about the vote, some detect more negative currents.
“We have a really large majority of students that are really engaged, but I would say that they are more angry than excited, because they don’t like the fact that they have been marginalized,” said Emily Harrison, president of the student union at Southampton University. “And of course, you do have some students who are apathetic, that feel like their vote doesn’t make a difference, so part of our campaign at the moment is to encourage students to vote.”
Charlie Corbett, 20, a first-time voter who has already mailed in his postal ballot, said he had registered only because his parents had pressured him. He stood out for not sharing his fellow students’ enthusiasm for defeating the Tories and Mr. Johnson’s drive to “get Brexit done.”
“I want to stay in the E.U.,” he said. “But at this point I’d rather leave than go around another five years in circles. I voted for Boris, he’s the only person who will get this done and that’s all I want at this point. Just to leave and move on.”