Former foreign secretary Margaret Beckett was tipped as the frontrunner in the race to become the next Commons Speaker as the contest entered its final 24 hours.
There were claims that the Government whips were pressing the case for the senior Labour MP as the bookmakers' odds on Tory John Bercow, the previous favourite, lengthened.
The bookies also suggested that another Conservative, Sir George Young, was making a late charge as MPs prepared to choose Michael Martin's successor in a secret ballot on Monday.
All of the candidates for the speakership were under scrutiny after fresh disclosures about their expenses claims.
Mrs Beckett could prove controversial with the public if elected as the next Speaker.
She was heavily barracked by a Question Time audience recently over her stance on the expenses scandal and faced further questions regarding her own claims.
She would also be the third Labour Speaker in succession and, having served as a minister for most of the past 12 years, is close to the Government.
But Labour MP Stephen Pound said he thought Mrs Beckett would win, thanks to the whips' involvement. "It isn't on," he complained on Sky News. "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."
Ladbrokes installed Mrs Beckett as the favourite, on odds on Sunday afternoon of 7/4, trailed by Sir George on 5/2 and Mr Bercow on 4/1 - all well ahead of the rest of the 10-strong field. William Hill put Sir George in front on 7/4, Mrs Beckett on 2/1 and Mr Bercow on 4/1.
Whoever becomes the next Speaker will be charged with restoring confidence and trust in Parliament after the events of recent weeks.
