Green Party leader Natalie Bennett visited Whitechapel Market to lend her support to John Foster, the group's mayoral candidate for Tower Hamlets.
The pair spent the day chatting to stallholders and customers about their election concerns, the impact of Crossrail and the Whitechapel Vision.
The poll to replace Tower Hamlets mayor Lutfur Rahman, who was removed by a judge over election fraud, will be held on June 11.
John said: "The Green Party are huge supporters of small business, and supporting our local economy is a major part of my campaign.
"Whitechapel Market is one of many markets in Tower Hamlets that are central to the community in Tower Hamlets.
"If elected as Mayor, I want to make sure any development coming in with Crossrail doesn't negatively impact existing local business owners."
The Green Party came third in Tower Hamlets in the recent General Election and achieved five times its vote compared to 2010.
Natalie said: "John is a fantastic choice as mayor for Tower Hamlets, and I hope many people support him with their first preference for Mayor on Thursday and vote Green in Stepney Green as well.