Employers were due to meet unions at the Scottish Council on Thursday to discuss the offer, which includes common terms and conditions for white-collar and manual staff, a£4 minimum wage and an average 2.5% pay rise.
Scottish employers say they have only budgeted for a 2% pay increase on salary bills this year.
Alex McLuckie, GMB public service section head in Scotland, said the union would sound out its shop stewards on strike action if employers renege on the offer.
Unison head of local government in Scotland Mark Irvine has written to the leaders of all Scottish councils warning that the union is not prepared to fundamentally renegotiate the pay and single status package.
'If members vote to accept the proposed agreement, Unison will be coming back to the Scottish employers to demand that the agreement is implemented retrospectively to 1 April 1997 as will be the case in the rest of the UK,' Mr Irvine told leaders.
All three main local government unions will have consulted their members on the offer by mid-June.
The T&G this week sent out ballot papers to its 100,000 local government members, recommending they approve the deal.
A Convention of Scottish Local Authorities spokesman said: 'The employers recognise that this is a national agreement and we have never reneged on a national agreement before. However, there are certain aspects of single status that need to be discussed before agreement is reached.'
It is understood that the employers will stick to the bulk of provisions in their original offer, with certain aspects tweaked after talks with unions. Unison has indicated that it is prepared to negotiate on the way the agreement is implemented.