Keir Starmer will say that a vote for Reform UK will put at risk progress Labour is making on the cost of living, arguing that Britain’s values are being tested in a volatile world.

Launching the party’s local elections campaign with a new slogan: “Pride in Britain”, Starmer will urge voters to stay the course with Labour. A dire set of results are predicted for the party in Wales, Scotland and English councils, especially in the north-east of England and London.

Starmer will put the focus on government action on the cost of living as he launches the campaign at a rally in the West Midlands alongside the Labour deputy leader, Lucy Powell, and other cabinet ministers.

But party chiefs have conceded the polls are likely to result in sweeping losses for Labour. These could include losing power in Wales after 27 years, with polls showing Labour lagging behind Plaid Cymru and Reform. The Scottish National party also looks set to deny Labour’s Anas Sarwar the chance for victory in Holyrood and many Labour councils could be lost to Greens and independents.

Starmer will list action on energy bills, the two-child benefit cap, the living wage and pensions increases as ways the government is tackling the cost of living, but will also cite the war with Iran as a reason to stick with the government, rather than risk change.

“We’re going to fight to earn every vote. Fight for our values. And fight for the country we are building together, a Britain built for all,” he will say. “Because, in the context of everything that is happening in the world, those values – that fairness we stand for – it’s never been more important.

“That is the thing about the volatile world we live in now. It tests, not just our security, our strength on the world stage. It is also tests our fairness at home. Our unity.”

Starmer will also attempt to draw attention to Kemi Badenoch and Nigel Farage’s early support for the US-Israeli strikes against Iran, which the government did not back, calling it “a question of judgment”. He will say: “Do not forget that the Tories and Reform would have rushed us into this. With no thought of the consequences, including for the cost of living. Utterly reckless.”

Labour said it held 7,000 local campaign events over the weekend, with 30 cabinet visits expected during the first week of the campaign.

Labour had previously attempted in campaigning to draw an equivalence between Reform and the Greens, a move that some Labour MPs reacted against. Party strategists have suggested they will not continue to use that framing and will instead accuse the Greens’ Zack Polanski of poor judgment.

Starmer will say on Monday: “While Reform have shown time and again they are not on the side of working people and the Greens offer the wrong answers for Britain, this Labour government is firmly focused on the pounds in people’s pockets.

“Labour has taken the fair choices needed to support families across Britain by expanding government-funded childcare, rolling out free breakfast clubs for kids, and widening access to free school meals.”

Labour is braced for heavy losses to Reform in the party’s former heartlands in the north-east of England, West Yorkshire and Greater Manchester. There is also particular concern about Birmingham, where there has been a long-running dispute over bin collections.

In London, where the party holds 21 of the 32 councils, there are several local authorities where significant Green gains are expected, especially Newham, Hackney and Lewisham.