Change MP elections to help save UK, says Mark Drakeford
Mark Drakeford has urged Labour to change the way MPs are elected at Westminster.
Wales' first minister said he is "baffled" by people who support first-past-the-post elections.
Labour should go into the next general election promising to reform the electoral system as part of a project to "save the United Kingdom", he said.
It comes after proposals for electoral reform were defeated at Labour's conference in Liverpool last month.
In first-past-the-post elections, the winner is the candidate which wins the most votes in a constituency.
It is used for Westminster elections, and to elect part of the Welsh and Scottish parliaments.
In a lecture, Welsh Labour leader Mr Drakeford called for the "repair of our democracy itself".
He pointed to the 2019 general election result in Scotland, where Labour won 19% of the vote, but only one seat.
"I have every sort of democratic quarrel with such a system, but for today I feel certain that its continuation will only feed further the fissures which threaten to prise the United Kingdom apart," he said.
He added: "How anyone clings to the notion that a system which delivers, so consistently, majority Conservative governments on a minority of the votes cast is best for working people simply baffles me."
A decision by the Unite Union - one of the Labour party's major backers - to back a new voting system makes the chances of reform "significantly improved", he says.
Mr Drakeford's Welsh government has supported calls to increase the size of the Senedd from 60 to 80 or 90 members.
A special Senedd committee is also looking at proposals to elect Members of the Senedd via the single transferable vote system.