Members of the London Assembly have backed a motion by 16 votes to one calling on Sadiq Khan not to sign a guarantee to meet the maintenance cost of the Garden Bridge in the event that private fundraising falls short.
We reported last week on the motion tabled by Labour's Tom Copley and Florence Eshalomi designed to put pressure on the Mayor of London to withhold his signature from the vital guarantee required before building work on the controversial bridge could begin.
At Wednesday's London Assembly plenary meeting, members of all parties represented at City Hall (Labour, Conservative, Green, UKIP and Liberal Democrat) spoke in support of the motion and against the Garden Bridge project.
Tom Copley argued that the bridge was the product of "cocktail-party cronyism" and questioned the amount of public money already spent on the bridge before construction work has begun.
Florence Eshalomi described the bridge as a "vanity project" and said that its transport credentials were far from clear.
For the Liberal Democrats, Caroline Pidgeon said that it was "far-fetched" to believe that the Garden Bridge Trust would ever be able to raise the estimated £3 million a year for maintenance without recourse to public funds.
The only assembly member present at the meeting who declined to support the motion was the Conservative Gareth Bacon who argued that if the Mayor wanted to pull the plug on the Garden Bridge project, he should have the courage to say so plainly.
However, his Conservative colleagues Andrew Boff and Keith Prince took a different view, backing the motion and making the case for spending on river crossings in other locations in London.
Mr Boff said that the Garden Bridge is "a truly wonderful project unless you wan to use it, live near it or pay for it".
UKIP's David Kurten went so far as to denounce the Garden Bridge as a "white elephant" and call for a public inquiry into the scheme.
For the latest local news and events direct to your inbox every Monday, you need our weekly email newsletter SE1 Direct.
7,000+ locals read it every week. Can you afford to miss out?
Read the latest issue before signing up