Launching his bid to replace Jeremy Corbyn, Mr Smith evoked Tony Blair’s “Clause IV moment” – when the former prime minister controversially amended the passage to remove its historic commitment to mass nationalisation.
The former shadow work and pensions secretary also backed Mr Corbyn’s call for a war powers act to give MPs in Parliament a legal veto over any decision to go to war.
He repeatedly praised Mr Corbyn’s influence on the party but spoke of the need to create a “radical but credible” movement with policies to match the anti-austerity rhetoric. He told an audience in his Pontypridd constituency: “We know, Jeremy knows, he said it, it’s a disgrace.
“We have a wider gap between the haves and have nots in this country than any of us have known in our lifetimes and it is for the Labour Party, our party, to fight to reduce that gap.
“It is time for us in words to commit ourselves by rewriting Clause IV of the Labour Party’s constitution, the beating heart of our party.
“I want to rewrite Clause IV to put tackling inequality right at the heart of everything that we do.
“Every Labour policy has to be tested against that benchmark – is it going to reduce inequalities in wealth, in power, in outcomes and opportunities, or is it not?
“And if it is not going to reduce those inequalities, then we in the Labour Party should not do it.”
In a move to win over the party’s members, who propelled Mr Corbyn to the top job, Mr Smith committed to creating a shadow cabinet and cabinet of Labour members to speak to the leader.
“I think it’s an important way in which we can reconnect our party,” he said.
He said although he supported Mr Corbyn’s anti-austerity “slogan”, Labour were “not on the pitch” in political debate.