Prime Minister Theresa May has vowed to reform the London mayoral elections, bringing them under the same system currently used for national votes.
London mayor Sadiq Khan was voted in last summer under the supplementary vote system, which allows voters to choose a first and second preference candidate for the role.
This is designed to ensure the winner of the election gains the support of at least 50 per cent of voters.
However, the Conservative election manifesto has committed to scrapping the system, and instead replacing it with the "first past the post" system.
This allows voters to select only a single candidate, meaning the mayor would simply be the most popular candidate after a single round, regardless of the actual level of support won.
It is not clear whether the reforms would also extend as far as the London Assembly elections, which take place on a proportional representation system, meaning that securing 10 per cent of the vote secures a party ten per cent of the seats in City Hall.
By contrast, first past the post is less reflective of broader voting and can bias towards the largest parties.
The Conservatives also said they would scrap the Fixed Term Parliaments Act, which previously established a regular cycle of General Elections for Westminster every five years.
May decided to override this legislation in order to secure the June election, winning the backing of more than two-thirds of MPs in the process.