Election officials are in talks with ministers over contingency plans in case strike action by council workers disrupts the local elections on May 4.
David Monks, chief returning officer for England, told Guardian Unlimited there were "strong rumours" that concerted strike action is being considered by 11 local government unions for May 3 and 4 over plans to change existing council workers' pension arrangements.
Voters across 176 local authorities are due to go to the polls on Thursday May 4, including all-out elections across the 32 London boroughs.
Mr Monks said talks are already under way with electoral administration minister Bridget Prentice, as well as the Electoral Commission, the police and the Royal Mail, to put in place contingency plans in the event of industrial action.
Mr Monks said Ms Prentice had been "sympathetic" to the possible plight of returning officers, who fear the democratic process could grind to a halt.
A strike could affect both the availability of polling stations, often situated in schools, and the staff to preside over the ballot and count the returns.
"We need access to premises," Mr Monks said.
"It is also a problem if staff refuse to count the vote that night because we would have to count votes on the Friday (May 5) rather than on Thursday night. So it could be that the results could be delayed."
Some returning officers have already lobbied their staff to ensure they will continue to work on election night regardless of the strike.
This is on the basis that local election work is paid separately as a one-off service provided by staff to the council, said Mr Monks, who admitted he has already talked to his own staff at Huntingdonshire district council.
"We have approached staff who went on strike two weeks ago and asked whether they would go on strike on polling day and they have said they will not," he said.
"They feel their grievance is not related to the exercise of franchise."
Unions insisted that "no decision" has been made about possible strikes beyond two days of rolling action planned across the regions later this month, which will run from April 25-27, following a successful one-day national strike staged last month.
The national joint trade union strike committee will meet this Wednesday to discuss progress on talks with government over the impasse, and the prospect of further strike dates.
A Unison spokeswoman said: "We have not made any decision. As far as we are concerned we are looking at regional rolling action which we have already announced for April 25-27. Nothing else is being considered at the moment."
Local government unions have vowed to continue with rolling industrial action after the government refused to back down and offer council workers lifetime protection from a key change to the pension scheme which currently allows staff whose combined age and years of service adds up to 85 to retire at 60 on a full pension.
Council staff are the only public sector workers to face changes to their existing pension scheme; all other public sector workers have been offered lifetime protection, with future changes only affecting new recruits.
