Unions have reacted furiously to new legislation that would tighten rules on strike ballots and political donations.
Under the Trade Union Bill, a turnout of at least 50% of members will be needed to authorise action.
The government's plans to make strikes harder to organise has been criticised as a "brutal assault on the most basic of human rights" by Mick Cash, the leader of the RMT.
He also said that the government's plan "mirrors the actions of hard-right regimes throughout history".
He added: "The trade union movement will unite to fight this brutal assault on the most basic of human rights and that campaign will be taken into the communities who stand to lose access to safe and reliable services as this noose of the anti-union laws is twisted round our necks."
The motive for the changes to strike rules may be more complex than the government is prepared to admit.
The Trade Union Bill is getting its first reading in Parliament latter today. Various strict new measures are expected.
The Government has come under fire as it launches its biggest campaign against trade unions in 30 years.