Boris Johnson could lose his seat, and this young Labour candidate hopes he'll be the one to take it

As Britain's Parliament was dissolved and the nation's first December election in a century got under way Wednesday, Ali Milani was wrapping uphis first cold, wet,night canvassing.

He insists he barely noticed the miserable weather.

"You can tell your kids when they grow upthat I unseated Boris Johnson that would be something!" Milani gushed to a supporter who stopped by to say hello near where his canvassers were gathering at the South Ruislip tube station in northwest London.

That's obviously premature,but the 25-year-old from thesuburb of Uxbridge will nonetheless be at the centre of one of the most closely watched races of Britain's Brexitelection on Dec. 12.

Prime Minister Boris Johnson has run in theconstituency ofUxbridge and South Ruislip twice,first in 2015, when he won handily, and again in 2017, when voters swung hard away from the Conservatives,cutting Johnson's margin of victory to 5,000 votes.

By Canadian standards, that still seems a pretty healthy margin of victory, but within Conservative circles in Britain, it set off alarm bells.

Labour hopes for historic upset

Now, the Labour Party and Milani have what they believe is an opportunity to accomplish an unheard-of double upset, not only by knocking off a sitting prime minister but stopping Johnson's Brexit plans at the same time.

"The energy is there for us to not only defeat the Conservatives but make history by unseating a prime minister in his own seat for the first time in British democratic history," Milani told CBC News.

Milani immigrated to the U.K. from Iran with his family when he was five years old and grew up in a working class neighbourhood.He cut his political teeth in student politics at nearby Brunel University, where he headed the student union, and he comes across as a political veteran despite his age.

"It's something that has not occurred,certainly in modern party politics," said Catherine Haddon,who studies the British parliamentary system at the Institute for Government.

And while she won't offer an opinion on how likely it is that Johnson would go down,she says it would have enormous implications for the Conservative Party and the Brexit legislation that Johnson is trying to push through.

"It would complicate things massively."

PM without seat would be unsustainable

The British political tradition is somewhat different from Canada's when a leader is defeated but his or her party manages to win.

Canadian Prime Minister William Lyon Mackenize King lost his seat twice in 1925 and 1945 but both times ran again and won in a byelection and stayed on as PM.

More recently,former B.C. Premier Christy Clark lost in her Vancouver riding in 2013 but ran again and won a few months later in Kelowna and carried on governing.

No such precedents exist in the U.K. parliamentary system,however, says Haddon.

"It's perfectly possible that a prime minister could stay on temporarily," she said. "It's not a must that you have to be an MP and a party leader,but there is [an]expectation that you should be, and that it would be unsustainable for a long period of time."

If the Conservatives were to win a minority of seats with Johnson being defeated,she says, that sort of "hung Parliament" would create even more uncertainty.

Some observers have mused about whether a defeated prime minister could appoint himselfor herself to the House of Lords and keep going,but Haddon says it's doubtful.

"Politically,I think it would be all but impossible to do that, and I think there would be pressure from his own party to resign."

While Johnson may have been "vulnerable" in previous elections, he wasn't prime minister then, said Daily Telegraph associate editor Camilla Tominey. That position comes with extra prominence and recognition that, she suspects, will help him withstand Labour's challenge.

"It's still one worth watching," she said.

'Brexit delay is holding us back'

The latest polls give the Conservatives nationally a lead of 11 percentage points over Labour, but with torn allegiances over Brexit, there's a lot of potential for surprises on election night, said Tominey.

Johnson did not start the campaign in the Uxbridge area,instead delivering a speech outside the prime minister's residence at 10 Downing Streetbefore heading to a rally in northern England.

"The whole Brexit delay is holding us back," he told a crowd in Birmingham, before drawing on an analogy from his time as mayor of London.

"It's like a bendy bus.I banned them in London. A bendy bus jackknifed, and no one could get around it.It's blocking the traffic in every direction. And the uncertainty and delay are bad for the country."

WATCH: Boris Johnsonis focused on Brexitbut one young politician is focused on making him fight for his seat

Brexit the focus of Britains election campaign

5 years ago

Duration 2:02

The British election campaign officially started today with the focus firmly on Brexit.

Divisions within parties makeoutcome unpredictable

Labour Leader Jeremy Corbyn, who remains deeply unpopular inside and outside his party,has promised to put Brexit to another referendumbut not before negotiating a new deal with the European Union and giving voters the choice to accept itor remain in the EU.

However, Corbyn has created confusion by not saying on which side he'd campaign.

The third-place Liberal Democrats have vowed to revoke the result of the 2016referendum and keep Britain in the EU,but Tominey says the move may alienate some of their more moderate supporters.

"So, we have a situation where at the heart of every party in politics in Britain at the moment, there are divisions that are muddying the waters when it comes to predicting what will happen on Dec.12."

Johnson appears to be counting hard on voter exhaustion with Brexit and hoping that after almost three years of non-decisions and failed efforts,people just want it over with.

On the streets of Johnson's constituency Wednesday,Theresa Hodgson told a CBC News crew that's exactly how she feels about it.

"I did vote for him, and I would vote for him again because I think he shows a lot of courage where no one else seems to."