Andy Burnham has promised that Labour will fight the next general election on a pledge to change the UK’s voting system.

In his first party conference speech as prime minister, he announced plans for a national commission to explore options for electoral reform.

He invited other parties to work with the commission to ensure “everyone’s vote counts, and everyone’s voice is heard”.

He has previously supported moves towards a proportional representation (PR) model, telling last year’s conference that “PR’s time has come”.

Westminster’s first-past-the-post system, under which candidates with the most votes in each seat are elected, has been called into question as the UK political landscape has fragmented in recent years.

Debate over the system has intensified since Labour amassed a huge parliamentary majority with a 34% vote share in 2024.

Around 100 Labour MPs recently supported a parliamentary amendment in favour of setting up a commission to examine alternative options, a move Burnham himself supported last year when mayor of Greater Manchester.

In his speech Burnham told delegates: “We will all have failed in our public duties if we carry on as we are and open the door of No 10 to a divisive government on less 30% of the vote or less.”

He added: “We can’t succeed in the eyes of the world if we continue with the levels of political turbulence we have seen in recent times.”

Burnham did not set out details of who would lead his proposed commission, or when it would begin its work.

Any move to change the voting system would be supported by the Liberal Democrats, who had previously urged Burnham to introduce proportional representation before the next election, which must be held by 2029.

However, any move away from first-past-the-post is likely to be resisted by the Conservatives. Reform UK backed introducing PR at the last election, but there has been speculation that its enthusiasm for the move may have since cooled.

Support for changing the voting system is also not universal within Labour, with deputy leader Lucy Powell acknowledging after Burnham’s speech that “parts of the Labour Party” are not in favour of it.

Speaking to Politics Live on BBC 2, she said she personally backed electoral reform but declined to specify a proposed new system, adding there were “lots of models” available.

At the last UK election the Liberal Democrats backed the introduction of a single transferable vote (STV) system, which is used for Scottish council elections.

Other options include the additional member system, a hybrid model that combines first-past-the-post with regional party lists that is used to elect members of the Scottish Parliament.

Earlier this year, the Welsh Senedd was elected for the first time using a closed-list proportional representation system.