The first minister of Wales has described devolution as “the UK’s greatest strength” that could also help prevent independence movements.
Mark Drakeford also told the Labour party conference that Boris Johnson’s government was “incompetent” and “one of the most awful we have ever seen”.
He said Labour should point to its electoral success and record governing in Wales and in town halls in England and Scotland in order to build credibility for a UK general election.
At the Labour conference in Brighton, Mr Drakeford said: “Everything that Labour has achieved in Wales, across England and Scotland, has been achieved in the teeth of one of the most awful UK governments we have ever seen.
“Incompetent to its core, automatically hostile to anyone who does not share its viscerally reactionary instincts, at home or abroad.”
He added that a reformed UK with more devolved powers could be kept “together by consent”, and hinted it may prevent independence movements, like that in Scotland, unhappy with the current arrangement.
Mr Drakeford said: “Just imagine what we could do if we had a UK Labour government committed to renewing and rebuilding the United Kingdom so that it genuinely works for everyone.
“A new relationship built around mutual respect, proper participation, one that recognises devolution is the UK’s greatest strength, not its greatest mistake, that the radical redirection of power to local places is the way we keep the United Kingdom together, together by consent.
“A new union that only Labour can offer and a country built again on Labour values to which people in all parts of the United Kingdom would want to belong, would choose to belong.”
Mr Drakeford also said Labour should point to its “success stories” in local government and devolved administrations, as they could help “win the next general election”.
“Because it in these stories that we find a compelling answer to one of the most difficult challenges that all of us in the party face,” he said.
“And the longer we are in opposition, the more insistent the challenge becomes: Even if our policies are popular how can voters be confident that Labour can translate those ideas into practice and on the ground?
“The answer is simple, and the answer is because Labour is already doing it.”
In November last year, the British prime minister is alleged to have described devolution of power to Scotland as his predecessor Tony Blair’s “biggest mistake” and as a “disaster”.
In recent weeks, opposition MPs from the SNP have raised concerns about bills making their way through parliament, including the Subsidies Control Bill, claiming they are a “backdoor” method of taking powers from devolved administrations and giving it to the UK government.