The opening 100 days of the first Conservative-only government since 1997 have been disastrous for workers' rights, trade union leaders said ahead of the early milestone for the new regime.
David Cameron's administration has made reforms to strike laws a priority since being freed of the shackles of five years of coalition with the Liberal Democrats.
The Prime Minister is expected to hail what he sees as the main achievements made since the general election on May 7 when he returns from a family holiday in Portugal.
But TUC general secretary Frances O'Grady said he was intent on tipping the balance too far in favour of employers, with protests expected to mount over the coming months.
"This Government has set its sights firmly on undermining the right to strike with the publication of the Trade Union Bill," she said.
"Measures like allowing employers to use agency workers to cover the jobs of striking workers, and requiring workers to give 14 days' notice of what they plan to post on Facebook during a strike will shift the balance of power in the workplace too far in the favour of the employers.
"Together, the Government's trade union proposals will mean workers can't defend their jobs or pay, stand up for decent services and safety at work."
Joining the criticism, Unite general secretary Len McCluskey said the first 100 days had shown how "divisive" the Conservatives were.
"Democratic governments do not plunge their citizens into such powerlessness. Yet this first full Tory government in 19 years embarks on an angry, regressive programme, not one element of which answers the big questions of the age.
"Where are the plans for home-building, for creating decent jobs that can give people a place in their communities? How can we bring our infrastructure up to speed to the benefit of all the country, not just preferential patches?
"Why are our young people being abandoned by this Government - and how on earth will this ensure the skills and engaged citizens we need for tomorrow? What services do our people need - and will there be anything left once George Osborne is finished?
"Since May, Mr Cameron has chosen not to position the world's sixth richest country confidently, fairly for the future but to blow further clouds of fear across the horizon - following on from fear of Scotland we now are encouraged to fear union members and the poor. "
Labour leadership contender Yvette Cooper claimed the Tory administration was "very nasty" and was set to launch an "ideological assault" on public services.
She acknowledged that the increase in the minimum wage had been a "good thing" - and something Labour had campaigned for.
But she told the Press Association: "I think overall, if you look at what they have done, they have ripped up a whole series of promises which they made to the electorate, which I think is taking people for fools.
"They promised they wouldn't cut child benefit - they are cutting child benefit. They promised they wouldn't cut child tax credits - they are cutting child tax credits.
"They promised they would cap social care - they are not. They promised the transpennine rail route - it has been shelved.
"Time and again the things they said they would do in order to get votes they have ripped up afterwards.
"And now they are coming along with a plan for 40% cuts in public services which goes way beyond anything that you need to cut the deficit and is just an ideological assault on the public services. I think this is a very narrowing, very nasty Tory Government that is setting out a very ideological stall for the next five years. We have got to be strong enough to take them on."