About 300,000 voters have disappeared over the last two years, a Labour MP has said in the run-up to this June's local and European elections.
Voters are disappearing, says Alan Whitehead
Former minister Alan Whitehead says the number of people signing onto the electoral register has nosedived to 70% in some inner city areas.
That is worrying when only half of registered voters turn out, he says.
Election organisers blame disengagement with the political process and rising problems in reaching potential voters.
There is currently no national electoral register but figures from the Institute for Democracy and Assistance (IDEA) suggests as many as 1.5 million people may not be registered to vote.
There are currently 44,403,238 voters registered - out of 45,804,132 people who are of voting age - but that does not take account of those barred from elections for other reasons.
Mr Whitehead points to the growing difference in some areas between the number of people recorded in the 2001 census and those on the voting rolls.
He told BBC Radio 4's Westminster Hour that election officials were finding it hard to get registration forms to the increasing number of people living in houses with multiple occupiers or flats.
"To some extent, these people are being written off the electoral register," said Mr Whitehead.
"And increasingly, that means that in some parts of the country where we have a worry about a 50% turnout, it's 50% of 70% and that is a very low turnout indeed."
The Southampton Test MP wants new ways of contacting potential voters to be explored, including allowing people to register by telephone, text message or e-mail.
Electoral laws passed in 2000 allow electronic registration, although this cannot be used while signatures are needed for the process.
Mr Whitehead says the fact that the registration problem was particularly bad in inner city areas ought to worry Labour as voters could be disappearing in the party's traditional strongholds.
'Why bother' attitude
Malcolm Dumper, from the Association of Electoral Administrators, said registration in his area of Southampton stood at an estimated 95%, but other areas were experiencing significant problems.
"We undertake a fairly robust registration campaign linked to a number of advertising initiatives," Mr Dumper told BBC News Online.
"However, we have found over the last few years that getting people to register is becoming more difficult."
Disillusionment with the political process did not help as people not intending to vote did not want to register.
But increasingly numbers of houses in multiple occupation, coupled with security systems making it more difficult for registration officials to contact voters, were also factors.
Mr Dumper said: "There needs to be a complete rethink about registration."
Local councils were looking at using electoral registers for checks on bus or leisure passes as a way of showing people that registration had other benefits apart from voting, he said.
And similar links could be made if national identity cards were introduced.
Voters ought also to be able to register more readily in public places like libraries, he suggested.
The Electoral Commission watchdog has launched a television and radio campaign featuring two animated characters, Mike and Tom, to encourage people to register and vote in June's local and European elections.
It stresses that the electoral registers are now updated every month so people can update their details at any point in the year.
Tuesday is the deadline for registration for the June elections.
Of those people surveyed by Mori last year about why they were not registered:
- 9% said they were not eligible to vote
10% said they did not know how to register
23% said they had "just moved house".