The Conservative-Liberal Democrat coalition running Birmingham City Council is in danger of its first defeat in three years - over wheelie bins.
A proposal to experiment with wheeled bins for garden waste and recyclable rubbish has split the parties, with Tories demanding the idea be rejected while a significant proportion of the 32-strong Liberal Democrat group is believed to be in favour.
Matters will come to a head on Tuesday when the full city council considers a scrutiny committee recommendation to press ahead with trials in constituencies where local councillors support the idea.
With the 41 Labour councillors certain to back the scrutiny recommendations, only 20 Liberal Democrats will need to vote in favour for the wheelie bin proposals to get council approval.
Martin Mullaney, who chaired the scrutiny inquiry, will attend a meeting of his own Liberal Democrat group tonight in an attempt to persuade colleagues to support the committee's recommendations.
He wants to give constituency committees until August next year to come forward with proposals for wheelie bin pilots covering rounds consisting of 7,500 households.
The cost of buying enough bins for 30,000 properties would be about £1.5 million.
But after two years the cost per household would be cheaper than continuing with plastic refuse sacks because fewer employees are needed to empty the bins, according to the committee.
Coun Mullaney (Lib Dem Moseley & Kings Heath) said most of his backbench colleagues were in favour of experimenting with wheelie bins but he feared Liberal Democrat members of the cabinet and other senior councillors would be "sat on" and urged to vote against or abstain.
He said the item had been placed at the end of a long agenda in the hope councillors and the press would have gone home before the vote.
Conservative councillor Tim Huxtable, a member of the scrutiny team, will attempt to have the wheelie bin recommendations over-turned at the council meeting.
He already has the support of the cabinet, which includes three Liberal Democrats.
A statement issued on behalf of the cabinet described the scrutiny findings as "weak and fundamentally flawed".
An assumption in the report that two operatives could empty 7,500 bins would require each bin to be wheeled from the doorstep to a refuse lorry, emptied and wheeled back again within an impossible timescale of 25 seconds, according to the cabinet statement.
The statement added: "We are committed to listening to our citizens and they have repeat-edly made it clear what they want. They want plastic sacks/bags for green waste, they want boxes for multi-materials and they want a choice of boxes or bags for paper and that is precisely what this administration has provided."
More than 360,000 properties in Birmingham will receive kerbside collections of green waste, paper and multi-materials by April next year.
The statement warned: "We recognise that we want to do more but we also believe strongly that we must keep things as simple and straightforward as possible."
Even if the vote goes against council leaders, the cabinet retains the power to over-rule scrutiny recommendations. Len Gregory, the cabinet member for transportation and street services, has made it clear that he will not sanction wheelie bin trials.