[custom_adv] It's a sweltering Sunday in late August and Ali Milani, dressed in a navy suit and clutching a wad of flyers, dabs at the beads of sweat gathering on his brow.The 25-year-old walks up the driveway of a redbrick house, on the outermost fringes of west London, and knocks. And waits. And rearranges his collar.No answer. "The problem with a sunny day like this," he says with a tight smile, "is that everyone is out." [custom_adv] Undeterred, Milani carries on his mission. Which is convincing voters in this Uxbridge and South Ruislip constituency to vote for him and boot out their current Member of Parliament -- who also happens to be Boris Johnson.If Milani pulls it off, it would be one of the biggest earthquakes in British political history.Never before has a sitting prime minister lost their seat in a general election. And while Johnson is yet to call an election -- though speculation is rife there will be one before the year is out -- Milani is wasting no time hitting the streets in his bid to oust the prime minister. [custom_adv] "Can you imagine," he said wistfully, "that moment when we stand on stage and the returning officer reads out the result ... a 25-year-old local resident has unseated the prime minister for the first time in history."It's not as far-fetched as it sounds. What was traditionally a safe Conservative seat has in recent years shifted to marginal. In the last election in 2017, Johnson's majority more than halved, to just over 5,000 votes. [custom_adv] The constituency was created in 2010, due to boundary changes, and has been Conservative ever since.Now it is classed as "vulnerable," according to the conservative think tank Onward, which took into account the growing number of younger voters in the area.Among them is this young Labour candidate and comic book fan whose favorite character is Superman. [custom_adv] Milani lumps Boris in the same basket as US President Donald Trump and Brazilian President Jair Bolsonaro, who he says represent a "brazen, right-wing, nasty style of politics." [custom_adv] He compared Johnson's privileged upbringing and Eton schooling with his own childhood growing up on a social housing estate and a single mother who "struggled to pay the electricity bill."