The toughest and most significant electoral battle of David Cameron's first term will happen next May, when Londoners go to the polls to elect a Mayor. Those outside the capital may bristle at the importance placed on these elections, seeing them as symptom of the media's obsession with the M25 beltway, but the election of a politician with the third largest personal mandate in Europe is not to be treated lightly.
The significance was not lost on the Prime Minister when in a breathless phone call to Boris Johnson he is reported to have said, "not only do I want you to win next year because we are friends, but I recognise that there is no way you losing would be seen as anything but a disaster for me."
For Ed Miliband the stakes are also high, as victory in London would provide the kind of momentum which would make it far more credible for him to get back into No10. Labour strategists scent blood as next year will be close to the mid-term of the coalition government, generally seen as the nadir of the electoral cycle for incumbents. After a low key selection campaign, Labour selected Ken Livingstone as its candidate again, ensuring a re-run of the 2008 contest.
There is a certain irony that the fate of both party leaders lies with people they have an uneasy relationship with - who represent a side of the party (old Etonian and old Labour) that they would much prefer to distance themselves from.
The polls indicate it will be a close run fight, with a YouGov poll in February showing Livingstone edging it by 3 points, but a more recent poll in June showing Boris ahead by 7 points. The key battleground will be for first preference votes. At the last election, Boris won clearly on first preferences: even though Labour narrowly got more second preferences, they would have needed 84% of these to win. In 2008, Labour actually got more votes in the first ballot than they did in 2004, but the Tories managed an extra 1 million votes to get them over the finishing line.
Both Ken and Boris managed to squeeze the smaller parties at the last elections, with only 260,000 first preference votes not being cast for Labour or the Tories. A recent YouGov poll indicated the Lib Dems expected to only get 2% of the vote, though this will increase when they finally select a candidate. Senior party officials are pulling out all the stops to prevent Lembit Opik, whose appetite for women and quiz shows has made him a Z list celebrity, from being the official candidate, with many thought to favour the little known Mike Tuffrey, a safe pair of hands Assembly Member who once led the party in Lambeth.
So what does Labour need to do to unseat Boris? The first thing is to run an election campaign which is completely different from the normal strategy in local or parliamentary elections of targeting marginal wards. As London is one big constituency of 5.5 million, Labour needs to increase the turnout in its safe, inner London areas where voters are less inclined to come out and vote than in suburban, Conservative areas. In 2008, Labour won narrow victories in its safe seats, by a few hundred votes, while the Conservatives piled up votes for Boris by 1,000 votes or more in areas like Bromley. At the same time, Labour needs an average swing of 3.1% (not inconceivable) across all GLA seats to win on first preferences.
Ken's team have learnt the lessons from the last elections, when the Tories managed to portray him as a Zone 1 mayor, and pile up votes in outer London seats, in what was dubbed the 'donut strategy'. The challenge for Ken is to appeal to voters that feel disconnected from central London - those who do not live on the tube network, might have a Kent postcode and don't commute into zone 1, but live and work locally. An entirely different set of issues will motivate them to go to the polls next year. At the same time, Ken has to engage with those voters who abandoned his coalition last time, especially such as the white working classes, LGBT voters, the Jewish community as well as first time voters who will not remember his time in office either at the GLC or the GLA. He is holding a series of 'Tell Ken' events across London, particularly in outer boroughs to demonstrate he is listening to people's concerns.
The final element is to make the election a choice between Labour and the Conservatives rather than a straight personality fight - Labour is more popular than Ken personally, and Labour is said to be 20 points ahead of the Tories in London, according to internal Conservative polling. Boris's strategy is simple. He has to spend the next 10 months distancing himself from David Cameron and the coalition as much as is humanly possible, something which has been agreed with No10. So expect to see more articles like his one in The Sun which slammed a 'soft justice' system the day before Ken Clarke announced plans on sentencing reform.
While Boris is allowed to go off-piste by Conservative high command, Labour is desperate to pin him down as a 'True blue Tory'. They point to the appointment of Eddie Lister, Thatcher's favourite council leader to his Mayoral team, in addition to cuts to transport funding and police numbers as evidence of his right wing credentials.
Whatever happens over the next months, it will be an incredibly tough fight. They may not be spring chickens any more, but both Ken and Boris are two of the canniest politicians in the UK right now.