Government proposals to tighten rules on strike ballots and political donations have been condemned by furious trade unions as "chilling" and "an attack on workers' rights and civil liberties".
Under the Trade Union Bill - the Conservatives' biggest assault on the unions since the 1980s - a turnout of at least 50% of members will be needed to authorise action.
In key public services - such as health, education, fire, transport, border security and energy - there will be an additional hurdle that a strike must be endorsed by 40% of those entitled to vote.
The package would also ensure that union members had to actively "opt in" to political levies - the proceeds of which are overwhelmingly paid into Labour coffers - and reduce restrictions on firms' use of agency staff.
Business Secretary Sajid Javid said the Government was delivering a "key commitment" from the Tory manifesto.
"Trade unions have a constructive role to play in representing their members' interests but our one nation government will balance their rights with those of working people and business," he said.
"These changes are being introduced so that strikes only happen when a clear majority of those entitled to vote have done so and all other possibilities have been explored."
The TUC condemned the proposals, saying it will become much harder to get a pay rise of defend terms and conditions in the workplace and that employers would be able to break strikes by taking on agency workers.
TUC General Secretary Frances O'Grady said: "This Bill is an unnecessary attack on workers' rights and civil liberties that will shift the balance of power in the workplace.
"If ministers were really interested in improving workplace democracy they would commit to online balloting. However, they would rather silence protests against their cuts to children's centres, libraries and social care services.
"These new restrictions on facility time will make it more much difficult for trade unions to solve problems at work before they escalate into disputes.
GMB General Secretary Paul Kenny said the Conservative plans were "blatantly one-sided" and would "poison" workplace relationships.
"When workers jump through the draconian hurdles required for their vote for strike action to be lawful employers can ignore the will of their own workers," he said.
"It will lead to even more trouble."
Mr Kenny said the proposals for scrapping automatic enrolment to political levies were designed to damage Labour.
"It is clear that the Tory Party High Command intend to make the Labour Party bankrupt by cutting off the main source of funding that they have relied on since the 1930s," he added.
"This is a completely one sided approach to party funding."
Dave Prentis, general secretary of public services union Unison, said: "These spiteful proposals will deny millions of ordinary workers a voice at work. Strikes are rare and the decision to lose a day's pay is never an easy one - especially for public sector workers who have suffered many years of pay restraint."
Chris Keates, general secretary of teachers' union the NASUWT, said the Bill was part of a wider government campaign to trample "those who fight for the rights of working people".
"The Trade Union Bill and all this other legislation have a chilling common theme, to restrict, stifle and silence opposition and attack our fundamental democratic rights and freedoms," she said.
However, employers' groups welcomed the changes.
CBI Deputy Director-General Katja Hall said: "The introduction of thresholds is an important, but fair, step to ensure that strikes have the clear support of the workforce.
"Placing time limits on ballot mandates is an important measure to ensure industrial action is limited to the original dispute and not extended to other matters."
Consultations on the 40% strike ballot threshold for key public sectors, picketing rules, and use of agency workers will be open until September.