The decision by the five largest unions at Birmingham City Council to stage a strike in an attempt to overturn unpalatable aspects of a pay and grading review represents the most serious threat yet to the local authority's ruling Conservative-Liberal Democrat coalition.
It remains to be seen, however, how many employ-ees will actually respond to a call to arms next Tuesday.
What the unions did not spell out, but was soon made clear by council sources, was that only 4,462 of the 40,000 people affected by the pay shake-up had actually voted to strike.
Less than a quarter of union members at the Council House took part in ballots - and this on a subject that has supposedly infuriated local authority staff.
The council leadership may have thought it would escape industrial action because most staff - about 86 per cent - will be either better off or no worse off when the new system is implemented on April 1. But the scale of pay cuts in a review that was supposed to promote equality has clearly shaken a proportion of the workforce.
Even those who are going to be better off feel disgusted by the harsh treatment afforded to colleagues. And it is indeed impossible to see how anyone could possibly describe plans to dock wages by more than £16,000 a year for 81 employees as anything but grossly unfair.
It may be that the sight of closed schools, bin bags rotting on the streets and the knock-on effect of crematoria failing to open will force the council back to the negotiating table. Certainly, newspaper and television images of the country's largest local authority grinding to a halt, if indeed that happens, will alarm the Government.
There is one way in which the situation might be resolved, and that is for the council to reconsider its decision to base the pay and grading system around seven tightly-drawn bands rather than the 12 bands favoured by most of the local authorities that have implemented the Single Status reforms.
The unions argue that, by selecting a smaller number of bands, the local authority seeks to suppress wage rises and cut the overall pay bill. The council is equally insistent that it cannot afford the £12 million cost of widening the banding and reducing substantially the number of people likely to suffer serious wage cuts.
There are hopeful signs that union and council lead-ers are to continue talking to each other. They must go the extra mile to find a compromise.