Cameron says it is time for 'rubber to hit the road'
David Cameron has returned to work following his paternity leave with a warning to ministers of "significant challenges" ahead.
Chairing the first cabinet since the early summer, the prime minister said October's spending review would be the "time the rubber hits the road".
This is when the government will set out its full spending cuts programme .
The TUC warned Mr Cameron of industrial unrest, with workers facing a "pretty volatile cocktail of issues".
The spending review, on 20 October, comes after most Whitehall departments were asked to plan for cuts of around 25% as the coalition attempts to cut the budget deficit.
Speaking ahead of next week's TUC annual congress in Manchester, the organisation's general secretary Brendan Barber said there could be action over the public sector wage freeze, continued privatisation of services and pension cuts.
He promised a campaign by unions to defend public services and jobs, which he likened to the row over the poll tax when Margaret Thatcher was prime minister.
Mr Barber said: "The poll tax was defeated when government MPs returned to Westminster to report that their constituencies were in revolt.
"The poll tax offended the British people's basic sense of what's fair- so will the spending cuts.
"Every coalition MP with a small majority and every coalition MP who fought an election to oppose deep early cuts needs to feel the pressure from their constituents to change course."
Mr Barber added: "We have a pretty volatile cocktail of issues, such as the public sector pay freeze, threats of further privatisation, re-structuring of public services and major worries about security of pensions. It is a pretty potent mixture and there could be difficult disputes as a result."
The government has canvassed the public for ideas on reducing the deficit, via a Treasury website.
Chief Secretary to the Treasury Danny Alexander has written to acting Labour leader Harriet Harman and the five candidates to become permanent leader, urging them to submit their suggestions.
In it he said: "I very much hope the Labour Party will take this opportunity to engage constructively.
"The alternative is continuing down the same path of deficit denial that created this economic mess. Pursuing this approach won't work in opposition any better than it did in government."
The prime minister's official spokesman said: "The spending cuts are not something that the government would choose to do, but it is something the government is required to do because of the state of the public finances.
"We have the largest peace-time deficit and we need to get that under control and it is important to get the level of public spending down."
Mr Cameron returned to work this week after being off for three weeks, when his holiday was extended by the early birth of his fourth child, Florence.