Thousands of public sector workers, including top civil servants, are due to vote on strikes ahead of a crucial week for the Government as it faces the growing prospect of massive industrial action over its controversial pensions changes.
Members of the FDA, which represents high ranking Whitehall staff, and Prospect will be balloted on whether to take industrial action in protest at plans to increase their contributions by 3.2%.
The result of the two ballots will be known in mid-November, by which time other unions representing over a million teachers, head teachers, NHS and local government workers, will have announced the outcome of strike votes by their members.
The TUC is organising a day of action on November 30, which could see millions of workers stage the biggest day of industrial unrest seen in the UK for decades.
The FDA represents more than 19,000 senior managers, government policy advisers, diplomats, tax staff, economists, solicitors, prosecutors and other professionals working across government and the NHS.
Up to 25,000 teachers, lecturers and support staff will pile further pressure on ministers by staging a mass lobby of MPs at Parliament on Wednesday over what they have called "ruthless" pension cuts in the education sector.
Sally Hunt, general secretary of the University and College Union, said: "Educators from across the UK will descend on Westminster on Wednesday to speak to their MPs about potential changes to their pensions. Much nonsense has been spun about gold-plated pensions and the scheme's affordability.
"It is important that MPs understand that there has still been no proper valuation of the scheme and any increases from members will not aid their retirement, but go straight to the Treasury."
Meanwhile, several unions will take legal action this week to challenge the Government's decision to change the measure for uprating pensions from the Retail Price Index (RPI) to the Consumer Price Index (CPI).
The unions, including the Public and Commercial Service union, the Fire Brigades Union, the Prison Officers Association, NASUWT teachers union, Unite and Unison, argue that CPI inflation does not include housing costs and is usually lower than RPI.