Lib Dems say public sector pay would be key to post-election negotiations
Liberal Democrat leader Nick Clegg is set to announce that his party would be unwilling to form a coalition with another party if it did not agree to increase pay for public sector workers.
He will form a "red line" in any negotiations his party holds following the election, should a hung parliament occur.
The Lib Dems want to see public sector pay rise in line with inflation for a two year period from next year and then above inflation.
The Conservatives have said they intend to carry on "restraining" public sector pay, which rose by up to 1% in March.
The Labour party plan to "prioritise those on lower incomes" and based on evidence and the recommendations of review bodies.
Clegg will say: "Liberal Democrats will not enter a coalition with a party not prepared to back pay rises for people working in the public sector.
"They have paid more than their fair share, and now enough is enough."
It comes as all of the parties try to rally support from voters ahead of Thursday's election, with Labour set to focus on the issue of tuition fees, while the Conservatives will call on the public to "stop and think" about the "historic choice" they will make.