Unions are making final preparations for a huge strike by over a million council workers, teachers, civil servants and firefighters in bitter disputes with the Government over pay, pensions and spending cuts.
Ministers will be angrily attacked for their treatment of public sector workers during the industrial action on Thursday, which is set to be followed by further walkouts later in the year.
Health workers are set to be balloted for industrial action over pay, threatening the biggest outbreak of strike action in a generation.
Unions expect the Government to criticise the low turnout in ballots which paved the way for Thursday's walkout, amid expectation that the Conservatives will propose changes to balloting laws in next year's general election manifesto.
Prime Minister David Cameron pledged earlier this year that he would back tougher laws, including a higher threshold of those voting to take industrial action before a strike could go ahead. Business leaders have been pressing for a new law setting a target of at least 50% of those balloted having to vote in favour, an idea supported by the PM and other leading Conservatives.
London Mayor Boris Johnson has spoken of changes in balloting laws during previous strikes by Tube workers in the capital. But unions will argue that if the same restriction was placed on parliamentary elections, no MPs would be elected.
Cabinet Office minister Francis Maude said: "We are not relaxed about them [the strikes], but the point to make first is most public sector workers regard their duty to serve the public as being paramount, so most public service workers won't be going on strike on Thursday. It will be a minority and we don't know how many it will be.
"These strikes are based on ballots which are either with extremely low turnouts or, in some cases, with no recent ballot at all.
"The only teachers' union calling a strike, the NUT, is relying on a mandate in a ballot that was called nearly two years ago.
"Taking action, which if it is effective is going to damage the interests of children and a load of hard-working parents who just want to be able to go to work that day... it is really very irresponsible."
Interviewed on Sky TV, he also said there should be a rule that means a mandate expires after a certain amount of time.
Mick Cash, acting general secretary of the Rail, Maritime and Transport union, said: "Reports that the Tories are planning to ban public sector strikes and ratchet up their anti-union laws are nothing new and will meet the fiercest possible resistance.
"The front line of defence against cuts and austerity is the organised working class and that is why the Tories and big business want to tighten the legal noose around our necks. They will have a fight on their hands."
Paul Kenny, leader of the GMB union, said: "Not a single MP has secured 50% of those eligible to vote in their constituency. There are no proposals for changes even though the outcome of that vote has a lot more significance than workers voting for action for a decent pay rise."