Officers who administer elections on 5 May must try to operate a system condemned by a judge as 'wide open to fraud'.
Judge Richard Mawrey overturned the election of six Birmingham Labour councillors because of impropriety with postal votes which would 'disgrace a banana republic'.
This will leave staff at risk of legal action by aggrieved candidates, who could claim they lost because of electoral fraud.
Chris Game, senior lecturer at Birmingham University's Institute for Local Government Studies, said: 'There is no sign of increased resources for election officials. Those elsewhere will find themselves in the same position as Birmingham.'
To 'keep the election on its feet' when faced with a deluge of postal votes, Birmingham City Council chief executive Lin Homer threw 'the rule book out of the window', according to the judge.
However, he said she had not broken election law.
Ms Homer said: 'A lot of returning officers will be thinking, 'That could have been me'.'
New elections are expected next month in the Aston and Bordesley Green wards. Labour has appointed an official to oversee its campaigns in the city.
Ministers decided to make postal votes easier to obtain because of concerns about falling voter turnout.
But the judge found this had been done without safeguards and said: 'There are no systems to deal realistically with fraud.'
The government had ignored repeated warnings, he noted.
Malcolm Dumper, executive director of the Association of Electoral Administrators, said: 'There is no time for any change to legislation [for 5 May], so returning officers have got to operate the system as it is.'
Essential reforms would include requiring voters to make personal applications for postal votes, and powers for officers to validate applications.
'The big thing is to restore public confidence in postal voting,' he added.
The Department for Constitutional Affairs said it would 'consider carefully the full judgment'.
COMMENT - MINISTERS IGNORED REPEATED WARNINGS
By Mark Smulian
The Birmingham judgment means voters face a general election, and English county council elections, unable to have confidence in the probity of the voting system.
At least the government has shelved all-postal voting, following last year's trials. But measures to make postal voting easier, introduced in 2001 to boost turnout, remain in place. It is this that the horrified judge attacked, warning: 'Any would-be political fraudster knows [the system] is wide open to fraud.'
So open, indeed, that he found these two cases were 'part of a Birmingham-wide campaign by the Labour Party' to use bogus votes to counter the effect of the Iraq war on its support.
It could have been any party, anywhere. Any elections officer could find themselves facing mounds of stolen, or intercepted and altered, postal votes. But they have no powers or resources to investigate their validity.
Despite repeated warnings of trouble, ministers stuck their fingers in their ears and their heads in the sand.
The intention of increasing turnout by making postal votes more readily available was laudable, but implementation has been disastrous and reform is urgent.