Conservative incumbent and Labour challenger hit the tarmac as contest to take control of capital hots up
A white double-decker bus says "Better off with Boris", while a red one says "Better off with Ken". It will be left to the 5.8 million registered voters in the capital to decide on 3 May who they want to be the next elected mayor of London, while the candidates will be stepping up their campaigns next week.
Nominations will open on Tuesday as the formal race for the 2012 mayoral election begins against a backdrop of spending cuts, cost of living pressures and a lack of affordable housing in the capital.
Separate elections for the 25-strong assembly will be staged on the same day, but these will be overshadowed by the personality-led mayoral contest, which is fought under the supplementary vote system.
Twelve candidates, including five independents, have so far declared their intention to stand – but all eyes will be on Boris Johnson and Ken Livingstone as they head for a rematch. Polling has the two neck and neck in a race that will determine who gets to preside over the 2012 Olympics.
The formal election period kicks off on the eve of the coalition government's third budget. There is widespread anticipation that the chancellor, George Osborne, will announce the scrapping of the 50p top rate of tax for top earners – a move likely to be welcomed by Johnson, who has repeatedly criticised it as the mayor of a city in which more people fall into the £150,000 salary bracket than elsewhere in the UK.
Brian Paddick, the Liberal Democrat mayoral candidate who is standing again after coming third in the 2008 election, warned on Sunday that it would be "a tragedy" if the budget gave "tax cuts to the rich" at a time when ordinary families are struggling to make ends meet.
Paddick told BBC1's Andrew Marr Show: "I don't care whether it's a tycoon tax, a mansion tax or a 50p tax – what we need to do is make sure that the high earners are paying at least as much tax as ordinary families."
Any move to scrap the 50p rate will be seized on by Livingstone, the former mayor who has cast himself as the candidate for the "99%" against the "privileged 1%" he accused Johnson of defending.
Osborne declined to comment on speculation that the top rate of tax will be reduced, but made it clear he wanted to see "real and substantial progress on lifting low income people out of tax" .
Tony Travers, the director of the Greater London group at the London School of Economics, said both camps will be watching the measures outlined on Wednesday closely.
"Ken will be hoping that the announcement of a cut in the top rate of tax will make the Conservatives look out of touch, whereas Boris will be hoping that the package of announcements will signal that the Conservatives are the party of lower taxes," he said. "It will play differently in London than elsewhere."
Johnson, who spent his first two years at City Hall in the shadow of a Labour government, has made securing a better deal for Londoners from No 10 one of the campaigning bullet points in his nine-point plan for the future of Greater London.
He will highlight the way he ensured the capital escaped major cuts to key infrastructure schemes – the Crossrail project and tube upgrades – in the 2010 spending review.
David Cameron, who has made a Tory win in London his top priority for 2012, is widely expected to press home the constructive relationship between City Hall and his government when he campaigns with Johnson over the next few weeks.
Meanwhile, the Labour leader, Ed Miliband, joined Livingstone on the campaign trail last week as Labour seeks to cast the election as a "referendum on fares".
Livingstone's Fare Deal Express battle bus will be on the road next week to highlight his key pledge to reverse the fare rises introduced under Johnson's watch in January – averaging 5.6% – through a 7% fares cut in October which he says would save Londoners £1,000 over four years.
The former mayor says the costed plan would be funded from a £729m surplus in Transport for London's operating budget – a claim strongly disputed by the transport body chaired by Johnson which insists there is no surplus and "every penny of TfL's budget is accounted for".