Jenny Jones, Green Party candidate for London Mayor in 2012, said:
"London desperately needs fresh ideas for the new challenges which people are facing.
"Brian Paddick failed to inspire potential Lib Dem voters in 2008, and I think the same could happen again next year.
"He is a very experienced police officer, but I'm not sure he can get to grips with key issues like air pollution, health and dealing with inequality.
Jones concluded: "The Greens are the only party offering the kind of fresh ideas which could attract the large number of people who previously voted Lib Dem, but are now seriously worried about the kind of society this Government is creating."