John Bercow or Margaret Beckett could be knocked out of the contest for Commons Speaker unexpectedly early today because Labour MPs who make up the bulk of the voters are divided between two equally cynical paths of action.

Of the ten candidates, Mrs Beckett, who first served in James Callaghan’s Government more than 30 years ago, remains the favourite among bookmakers, while Mr Bercow, the Tory MP for Buckingham, has been steadily and quietly putting in months of work to secure the support of dozens of Labour MPs and Cabinet ministers.

His efforts have been lost on two of them: Gordon Brown has waived his right to vote and Alan Williams, the Father of the House, who presides over the election, cannot take part.

Among the remaining 347 Labour MPs there are two strands of thinking. This has split the party and may open the way for another candidate, such as Sir George Young, Tory chairman of the Standards and Privileges Committee, to sneak through the middle.

Publicly, Mr Bercow’s campaign is based on his reforming credentials and, on the Labour side, opposition to David Cameron, the Tory leader. His team says that his Cabinet backers include Harriet Harman, Alan Johnson, Ed Balls, Andy Burnham, Yvette Cooper, Douglas Alexander, Ben Bradshaw and Peter Hain.

Mr Bercow’s other Labour supporters, MPs such as the diehard Brownite Ian Austin, admit that their backing is not based on any great love for the Tory. Instead, they point to focus group research that shows that Labour is being damaged disproportionately by the row over MPs’ expenses because the public believes that Parliament is controlled by the Labour Government. They would prefer to see a Tory Speaker presenting reforms since they believe that this is the only way to break the perception that Labour should take the blame.

Supporters of Mrs Beckett see it differently. Many still feel wounded by the ignominious exit of Michael Martin, the first Speaker ousted since 1695, when Sir John Trevor was thrown out for bribery. Also, since Labour has the votes on its side (the Tories have only 193 MPs), they feel that they have every right to choose another Labour Speaker, dismissing arguments that, after Mr Martin and Betty Boothroyd, it is the Tories’ “turn”.

“The Tories have stuffed us so we have every right to stuff them back and vote for another Labour Speaker — they get what they deserve,” said one Beckett supporter.

Mrs Beckett, a close friend of the Labour Chief Whip, Nick Brown, has also been playing a slightly different game from the other candidates. At last Wednesday’s hustings in front of the Parliamentary Labour Party, she was the only candidate who did not promise to allow MPs to choose the chairs of select committees — plum jobs with £30,000 in additional salary. This is currently an important piece of patronage exercised by the whips and they are reluctant to surrender it, despite the promises of other candidates and party leaders.

Mrs Beckett is an unlikely reformer. She claimed almost £11,000 in gardening expenses, including £1,380 for plants. A claim for hanging baskets, tubs and planters in 2005, rejected by the parliamentary fees office, had been a “mistake”, she said.

The level of rancour between the sides rose considerably over the weekend. Martin Salter, the Labour MP for Reading and Mr Becow’s campaign manager, said: “There is a danger the Commons could end up making itself a laughing stock by selecting another traditionalist from the retired ministers’ club as a result of collusion between elements in both the Government and opposition whips’ offices.” Stephen Pound, a maverick Blairite, accused the whips of “touting” Mrs Beckett for the speakership. On Sky News, he tipped her to win but added: “It isn’t on. If any of the whips are out there are listening, stop doing it. We know what you’re doing, you’re going round touting Margaret Beckett.”

Yesterday Mr Martin used an interview in The Observer with Lord Hattersley, Labour’s former deputy leader, to take another swipe at his critics and insist that he could have held on to the post if he had tried.

The former sheet metal worker who has endured years of sniping since becoming Speaker in 2000 said that working-class Glaswegians were “too good to wipe the boots” of his detractors. He maintained that he was always up to the job but said he had become a “lightning conductor” in the expenses scandal. “I decided it was better to step aside than contribute to the disunity. I could have spoken to members and asked for their support, but to do that would have caused more disunity.”

He also acknowledged that the criticism of him and his wife, Mary, had been painful. He recalled an article in which a journalist “said she was only a steel smelter’s daughter. Not fit to be a Speaker’s wife. They must have gone to the trouble to look up her birth certificate.”

Mr Martin was looking forward to spending time at home in Glasgow. “I’m back to being 15 again, when I left school to start my apprenticeship. Then I had only two weeks’ holiday a year. Now I’m going to enjoy myself.”

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