Britain’s leadership contest starts a month-long nationwide tour on Saturday as Boris Johnson and Jeremy Hunt each seek to win over grassroots Conservatives in their bid to become prime minister.

After five rounds of secret voting by MPs in the governing Conservative Party, former London mayor Johnson and Foreign Secretary Hunt are the two final contenders out of an original field of 13 hopefuls.

The contest kicks off as the Guardian daily reported police were called to the home of Johnson and his partner Carrie Symonds amid a heated row in which she could be heard telling him to “get off me” and “get out of my flat”.

According to the newspaper, officers were alerted early on Friday after a neighbour said there had been a loud altercation involving screaming, shouting and banging at the south London property.

London’s Metropolitan Police said it responded to a call from a local resident but that “all occupants of the address… were all safe and well”.

As runaway favourite in the race to become PM, Johnson will now be hoping to avoid making any major blunders while out on the campaign trail, while Hunt will need to pull off a huge upset if he is to win.

Whoever takes the Tory party leadership in the week beginning July 22 — and therefore becomes prime minister — will then face the looming Brexit deadline of October 31.

The battle is likely to feature pledges from both contenders to get Britain out of the European Union safely and in one piece, succeeding where outgoing Prime Minister Theresa May repeatedly failed.

But the race might ultimately turn into a popularity contest between Johnson — pugnacious but affable with a tendency for gaffes — and the more diplomatic and low-key Hunt.

“Mr Johnson may stumble. His challenger must attack. It’s an outside chance. But there’s no other way,” The Times newspaper columnist Matthew Parris wrote.

“A challenger will never win on policy,” said the former Conservative MP.