The government has been urged to abandon "all-postal ballots" for this year's referendum on whether to create a Yorkshire and Humberside assembly.
A report into June's postal ballots will be released in September
The Labour MP Gordon Prentice told the Commons the traditional ballot box may be preferable after allegations of fraud in last week's postal elections.
Police have been called in to investigate a number of complaints in West Yorkshire.
It follows claims visitors to the UK and dead people had been given a vote.
Labour and Liberal Democrat politicians, from Bradford's Great Horton ward, handed a dossier to West Yorkshire Police detailing allegations of how voters registered as living in empty properties.
The document also claims some people who had been visiting Bradford from Pakistan had been entered on the city's voting register.
Mr Prentice said: "Do you think it's right that we go ahead with all-postal voting in the regional assembly referendums in October when the Electoral Commission is only going to publish its review of all-postal voting on 10 June in the previous month of September?"
Commons Leader Peter Hain told members there would be "plenty of time" to consider the recent pilot and the October vote was different as it was a choice of yes and no rather than a choice of a range of parties.
He added: "The blunt truth is, everybody lost the
"The Conservatives lost the European elections, Labour lost the European elections, the Lib Dems lost the European elections and UKIP lost the European elections and so did every other minor party."
Meanwhile, Deputy PM John Prescott is to launch an awareness campaign in York about what a regional assembly would mean for the Yorkshire and Humber area.
The government is hoping television, newspaper and billboard adverts will help tackle voter apathy ahead of the referendum.
Those campaigning for an assembly say it would give Yorkshire and the Humber a stronger voice in the political arena
People in the 'No' camp believe an assembly would mean more red tape.