Jeremy Corbyn will pledge to repeal the trade union bill if Labour is elected in 2020, as he sets out a range of measures to extend workers’ rights, including giving every employee a vote on executive pay.

The Labour leader will share a platform with the Scottish National party leader, Nicola Sturgeon, for the first time on Thursday evening at a Scottish TUC event in Glasgow opposing the bill, which has been described as the biggest crackdown on workers’ rights for 30 years. It includes plans to restrict the flow of union funds to the Labour party, and Liberty has called it a “major attack on civil liberties”.

Corbyn will tell the event: “I was elected on a platform of extending democracy in every part of the country and every part of society – giving people a real say in their communities and workplaces, breaking open the closed circle of Westminster and Whitehall and, yes, of boardrooms too.”

He will also announce a Labour commission for new rights at work to be led by Ian Lavery, the shadow minister for trade unions and former president of the National Union of Mineworkers.

“Not only will we repeal the trade union bill when we get back in in 2020, we will extend people’s rights in the workplace and give employees a real voice in the organisations they work for,” Corbyn will say.

“That means new trade union freedoms and collective bargaining rights, of course, because it is only through collective representation that workers have the voice and the strength to reverse the race to the bottom in pay and conditions.”

Accusing the Conservatives of tipping the scales still further in the direction of the employer, he will argue: “That same rigging of workplace power is what has led directly to the explosion in executive pay and boardroom excess, while low wages and insecure employment have mushroomed under Cameron.

“So what about giving every employee a real democratic say on executive pay? And what about transparency of pay, conditions, investment and employment decisions – to give employees and trade unions the means to have real influence over the crucial decisions that affect people’s working lives?”

The Scottish government has called on MSPs to block the legislation. On Wednesday, SNP ministers submitted a legislative consent memorandum asking the Scottish parliament to withhold consent from the UK government bill.

Under Sturgeon’s leadership, and with the former Unison activist and MP Chris Stephens leading on the bill at Westminster, the SNP has been making far more successful overtures to the trade union movement as it consolidates its position in traditional Labour territory in the run-up to the Holyrood elections in May.

In September, Sturgeon wrote to Corbyn to ask him to back a SNP amendment to the Scotland bill to devolve trade union and employment law from Westminster to Holyrood, a proposal backed by the Scottish TUC and the UK’s biggest unions, Unite and Unison. At the time Labour said it could not back this measure because it wanted to defend trade union rights across the UK.