By James Landale
BBC deputy political editor
The Speaker finds himself up against a host of other candidates
As a Conservative MP, John Bercow used to win huge majorities in Buckingham.
And as Speaker, he is being given a free run by the three main parties, which are following convention and staying away.
So on 6 May, you might imagine he would get an easy ride.
But in this leafy, rural seat in the heart of England, he is facing a challenge from a clutch of other parties and independent candidates who see him as a symbol of a rotten parliament - and they want him gone.
The most high profile threat is from UKIP, whose former leader, Nigel Farage, told me in a pub - where he seems to do much of his campaigning - that he was offering voters a choice in a seat that he says is being ignored by the main parties.
He says UKIP is giving voters the chance to send a message to the political classes that Mr Bercow is not the right man to restore trust in British politics.
In what is clearly a colourful election, one independent candidate - the former Tory MEP John Stevens - is campaigning with a dolphin called Flipper to remind voters that Mr Bercow was one of many MPs who "flipped" their homes to claim different expenses.
Others point to the fact that as a non-partisan Speaker, Mr Bercow cannot change the way voters in this seat are governed.
As the Speaker campaigned in Buckingham's street market, he set out for me his defence.
Nigel Farage seems to be doing much of his campaigning in pubs
First, that he claims to have been a good local MP, championing voters' interests, not least in opposing the planned London-to-Birmingham high speed rail line that he says would be a dagger through the constituency.
He says his position as Speaker means he can also summon ministers to discuss local issues - and they come.
Second, he believes that the people of Buckingham would prefer to be represented by a Speaker rather than what he calls a fringe MP.
Having spent the day talking to voters in Buckingham, several points are striking:
1. There are many voters who are angry that the three main parties are not standing. They feel disenfranchised. They want to join the Clegg bandwagon, or back David Cameron's big society, or vote Labour because they still see Mr Bercow as a Tory - but they do not have the choice.
2. Some voters - but not that many - do feel that Mr Bercow blotted his copybook in the expenses' row and are reluctant to give him their support as a result.
3. UKIP have a strong and colourful media campaign, but some local residents said they had not seen much evidence of the party campaigning door to door. UKIP's performance on 6 May will depend a great deal on how well they can pick up disenfranchised Labour voters and those angry at the political establishment.
4. As across the nation, there are a good number of voters who have yet to make up their minds.
Two issues point in Mr Bercow's favour though.
A lot of people I spoke to told me that Mr Bercow was an effective local MP.
They said that he replied to letters quickly, they had seen him out raising money for a local charity, he had helped one woman's mother with her pension difficulties, he had been seen in the library reading out the local paper so it could be recorded for the blind, he always remembers their names, and so on.
He clearly does his best to charm and nurture his electorate.
But perhaps most importantly, his opponents are divided.
There are a clutch of candidates standing against him and they have different positions - some are anti-establishment, some are anti-Bercow, others are claiming to be unofficial Tories.
In other words, the threat against Mr Bercow is disparate rather than focused and that should help him on polling day.
The full list of candidates in Buckingham is:
John Bercow - Speaker Seeking Re-election
Colin Dale - Monster Raving Loony Party
Nigel Farage - UK Independence Party
David Hews - Christian Party
Geoff Howard - Independent
Debbie Martin - Independent
Lynne Mozar - British National Party
Patrick Phillips - Independent
John Stevens - The Buckinghamshire Campaign for Democracy
Simon Strutt - Cut The Deficit Party
Anthony Watts - Independent