The UK’s main opposition Labour Party will attempt to deepen links with trade unions at a crucial gathering, amid criticism from two union leaders that leader Keir Starmer is failing to set out a clear vision for power.

In a speech to the Trades Union Congress conference in Liverpool on Tuesday, Labour’s deputy leader Angela Rayner will vow to strengthen workers’ rights and create good jobs if the party wins power at the next general election. “Joining a union changed my whole life” and “unionized jobs” are the key to boosting social mobility, she is expected to say, according to her office.

Labour is trying to strike a balance on workers’ rights as it seeks to hold onto its core supporters in the unions — who are also key financial backers — at the same time as winning over big business and former Conservative voters.

Starmer hopes to capitalize on waning support for Rishi Sunak’s Conservative Party, which is trailing Labour by around 20 points in the polls.

Labour has promised what it calls a New Deal for Working People as a “comprehensive plan” to create jobs across the whole of the UK. That includes banning zero-hour contracts, bringing an end to fire and re-hire, and repealing legislation that attacks the right to strike.

At the same time, the party’s efforts to reach out to corporate leaders as it tries to win power has generated suspicion among some trade unions.

Mark Serwotka, general secretary of the PCS union representing almost 200,000 civil servants, told Bloomberg it was “hard to get a straight answer” on whether a Labour government would support above-inflation pay rises, an issue which has seen hundreds of thousands of workers going on strike.

He also hit out at Starmer’s U-turns over policy since becoming Labour leader in 2020 — including on public ownership of services — saying: “That smacks to me of someone who is untrustworthy or believes they can say different things in different places.”

Sharon Graham, general secretary of the Unite union, told the TUC gathering that Starmer must be “bold.” Urging him not to simply follow the play book of Tony Blair, who led Labour to power in 1997, she said: “There is no point grasping for a policy mix stuck down the back of a 1990s sofa.”

Ahead of a planned meeting at the TUC conference on Monday evening, Starmer countered that there is “a lot of common ground” with the unions. “The Labour Party is absolutely focused on the future, not the past, and the challenges that we will inherit if we’re privileged enough to go into government,” he told reporters, according to the PA agency.