The incumbent Mayor of London’s campaign for re-election has received a boost from the Green party, who today urged their supporters to cast their second preference votes for him.

Ken Livingstone said his second preference vote would be going to Green candidate Sian Berry at the launch of their “Common Green Agenda” this morning.

In every London Mayoral election so far second preferences decided the outcome.

The Mayor of London is elected by the Supplementary Vote (SV) system, meaning voters may choose a first and second choice candidate.

After the first round, all but the top two candidates are eliminated from the race.

The second preference votes cast by people who supported lower placed candidates are then counted and added to the first preference totals of the two top placed candidates.

Tory Boris Johnson today called Mayor Ken Livingstone “arrogant” for telling people how to vote, while the Lib Dems’ Brian Paddick accused him of exploiting green issues for political purposes.

Siân Berry and Ken Livingstone issued the following joint statement this morning:

“Tackling climate change and creating a fairer London must be at the top of any serious Mayor’s agenda.

“Boris Johnson, who supported George W Bush in opposing the Kyoto Treaty and would scrap the CO2 charge on gas guzzlers, cannot be trusted with London’s environment.

“Nor can a man who opposed the minimum wage be expected to promote fairness or tackle poverty.

“London, with a committed Mayor and Green Party representation on its Assembly, has taken a global lead on environmental and social justice over the last eight years. Let’s keep it that way.”

Londoners will go to the polls on May 1st. For a full list of candidates for Mayor of London click here. Nominations close on 28th March.

The pact between the Greens and the Mayor comes as polling shows him lagging behind the Tory candidate.

Mr Livingstone today claimed that without the support of the Green party’s two Assembly members, funding for many of his environmental projects would have been blocked by the Conservatives.

“In this mayoral election, Sian Berry and I stand alone among the Mayoral candidates in our commitment to implement further groundbreaking environmental initiatives such as the £25 a day CO2 charge on gas guzzlers,” he said.

“Boris Johnson and Brian Paddick oppose the £25 a day CO2 charge for some 4x4s, high-powered sports cars, and luxury executive cars travelling in the congestion zone.

“All of the polls indicate that this will be a straight choice between Boris Johnson and myself.

“So I urge Londoners who vote for another candidate with their first vote to use their second vote to help decide that contest by voting for me to stop a Tory victory.

“I will be casting my own second preference for the Green Party because Brian Paddick calls for the London Underground to be privatised, has abandoned green Liberal Democrat policies to side with Boris Johnson in opposing the CO2 charge on gas guzzlers and the Low Emission Zone to cut pollution from lorries.”

Tory candidate Boris Johnson, said:

“This just shows how out of touch and arrogant this Mayor is that in a democracy he thinks he can tell people how to vote.

“Londoners will make up their own minds based on the policies put forward by all candidates.

“I have already published manifestos on crime, transport and housing and will be launching my environment manifesto shortly, which will include a number of fresh and innovative ideas for making the capital cleaner and greener.

“When will Ken Livingstone finally publish some policies? We can only assume that he has run out of ideas and will continue to borrow mine.”

Brian Paddick, who is the only gay candidate in the race, said:

“Anybody can exploit green issues for political purposes but the independent assessments of solutions to tackling climate change show the Liberal Democrats are the only party to have proposals that work.

“We have the record of achievement and commitment to making London the greenest capital in Europe.”

Gay equality organisation Stonewall is hosting a hustings event with the candidates for Mayor of London on Saturday 19th April, the last such event before Londoners go to the polls on May 1st.

Mr Livingstone, Mr Paddick, Mr Johnson and Ms Berry will be taking part.

The Stonewall hustings will be held on Saturday 19th April between 11am and 12.30pm at the BFI Southbank, London.

PinkNews.co.uk is proud to be a media sponsor for this event, which is open to everyone.

In order to ensure a seat you must register here.