Sir Keir Starmer has moved to keep union bosses onside by issuing a warning that failure to win the next general election would put them “in a very hard position”.

Unease between Unite and the UK Labour leader led to the union voting on whether to break away from Labour, although delegates voted overwhelmingly to maintain its affiliation with the party earlier this week.

In a speech to the union’s policy conference in Brighton, Sir Keir said both Unite and his party share the same goals although “our roles are different”.

Sir Keir said “we are nothing without power” and told the union “I make no apologies” for his approach to winning the next election.

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“If we lose it, if we go to the fifth general election defeat for the Labour Party in a row, that doesn’t help working people one bit,” he said.

The Labour leader has drawn trade union anger for moves to sideline left-wingers and a perceived lack of support in industrial disputes.

Unite general secretary Sharon Graham has warned that the fact that disaffiliation by the union, Labour’s main financial backer, had even been considered should be a “wake-up call” for Sir Keir that “workers are not happy”.

In his speech in Brighton, Sir Keir said: “When she speaks to me, when she speaks to the Government, when she speaks to anyone, Sharon never stops fighting for this union, and that’s right.

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“She has a mandate to fight for your jobs, pay and conditions, and she has made it very clear that’s what she will judge me on as well. And that’s how it should be.

“I accept that and I respect the relationship that Sharon and I have.

“We have different roles, different jobs, different ways of fighting for working people – party and movement.

“But our shared interest is, as it has always been, the economic security of working people.”

But Sir Keir defended his approach to the Labour leadership, which has seen him distance himself from the Jeremy Corbyn era.

“There is an opportunity here, a chance to tilt the direction of this country firmly and decisively towards working people,” he said.

“Win the battle of ideas, not just next year but for a generation.

“But look, there is one key word here: win. That’s my job and I make no apologies for pursuing that.”

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He told union members he would repeal the Government’s legislation on minimum service levels during strikes and bring in a new deal for working people.

“In this era, when the winds of change are blowing so fiercely, as they were in the 1980s, then, make no mistake, that prize is priceless.

“So we will stay focused, stay disciplined, keep our eyes firmly fixed on the future.

“Replace the chaos of Tory drift with the stability of Labour leadership.”

But, he added: “If we don’t win the next election, that legislation won’t be repealed. That new deal will be a document on somebody’s shelf, gathering dust, and you will be in a very hard position.

“Because you will have five more years of a Tory government and they will bring in further anti-union legislation.”