Jon WelchThe battle for Norwich South looks like being one of the most interesting of all. Sitting Labour man Charles Clarke faces a stiff challenge on three fronts for the constituency he has held since 1997.Jon Welch

The battle for Norwich South looks like being one of the most interesting of all. Sitting Labour man Charles Clarke faces a stiff challenge on three fronts for the constituency he has held since 1997.

Since taking the seat, the former cabinet minister has seen his majority cut over successive elections to just 3,653, leaving him vulnerable.

But to whom? The Conservatives, Greens and Liberal Democrats all fancy their chances and all argue they stand the best chance of ousting Mr Clarke.

A week into the campaign, all the major contenders are brimming with confidence. 'There's a great feeling on the streets and great relief the election has finally been called,' said Antony Little, Conservative candidate.

'The marvellous thing about elections is people set agendas, not parties. There's a very strong 'time for a change' theme running through all the conversations we have.'

Mr Little, who finished behind Mr Clarke and the Lib Dems in 2005, said: 'There's a lot of concern about the prospect of a hung parliament. People are concerned Gordon Brown may stay on as prime minister with support from the Liberal Democrats.

'A lot of people have been complaining about Liberal Democrat and Labour literature which claims certain parties are a wasted vote. I think the tactical vote message has had its day: people want to support the party they believe in. We think there are enough Conservatives.

'This election could be decided on less than 30 per cent of the vote: 12, 13 or 14,000 votes will win.'

Simon Wright, the Liberal Democrat candidate, said concerns raised on the doorstep so far had included cuts to local schools, the state of the economy, antisocial behaviour and the quality of public transport.

'The feedback I'm getting is very positive and I'm grateful for the warm reception. This will be a very close election and every vote will count. I'm expecting there will be a higher turnout than some are predicting. There's a real appetite for change,' he said. 'We're reminding people who the real challengers are in this election. The last parliamentary election was very close between Labour and the Lib Dems. I don't see the Labour vote as having collapsed but the Lib Dems are performing extremely strongly.'

Adrian Ramsay, Green candidate, said: 'I'm really pleased with how it's going and the response we're getting on the doorstep. People are excited that Norwich can lead the country in electing a Green Party MP.

'It's very close between Labour and Greens based on canvassing and the posters up around the constituency. It's the choice between more of the same or voting for a change.

'I'm finding most people are interested in the election and in discussing the issues. People are concerned about the recession and we have proposals to create jobs that will last by manufacturing more of our own goods and growing more of our food locally.'

Despite finishing fourth last time round, the Greens maintain they are the real challengers to Mr Clarke, pointing out that they have councillors in more wards across the city than any other party.

Mr Clarke, meanwhile, remains the bookmakers' favourite and admitted the lack of an obvious challenger played into his hands.

'There is no clear alternative, which from my point of view is very helpful,' he said.

'I feel confident. The campaign organisation has been very successful; we have got out our first round of leaflets and almost all our second round. There's a lot of positivity and enthusiasm.'

He was joined yesterday by Home Office minister Meg Hillier for a visit to the Thorpe Hamlet Surestart Centre at Wolfe Road, Norwich.

The centre had been earmarked for closure by Norfolk County Council, which backtracked on the plans after widespread local opposition.

Mr Clarke said a large part of his campaign was about highlighting the practical achievements of Labour for people in the city.

'It's about underlining the commitment we have to Surestart. We developed the programme and took it forward,' he said.

'This Surestart centre was threatened by a review of nursery provision by the Tory-run county council. There was a campaign, which I supported, which has kept it open.'