The Conservatives have highlighted concerns the voting system has become vulnerable to fraud and intimidation.
Dr Fox will warn the present system could "derail" a close election
Party co-chairman Dr Liam Fox accused Prime Minister Tony Blair of trading the integrity of the electoral system for narrow party interests.
The Times says election officers have been told to contact the police if anyone brings more than five postal ballot papers into a polling station.
Labour and the Lib Dems seek to turn their attention to plans for health.
In a speech to party workers in Somerset, Dr Fox said: "It is clear Mr Blair's reckless fiddling with the electoral system has raised widespread public concern about the integrity of Britain's electoral system.
"The electoral practices of the 18th and early 19th Centuries, such as intimidation and fraud, risk becoming the hallmark of the 21st."
His stance comes amid growing fears that the results of the general election could be challenged in a number of marginal constituencies.
"If the laws are not tightened, Britain risks a Florida-style deadlock that could derail any tightly-fought election," said Dr Fox.
His comments come after postal voting fraud scandals in local elections in Birmingham and Blackburn.
Concerns have also been fuelled by a large increase in the number of people registered to vote by post.
David Monks, leader of Britain's returning officers, told the Times mistakes were bound to occur as staff are under an "enormous strain" as they struggle to cope with the "extremely high" number of postal votes, compared to 2001.
He estimates that staff will have to deal with about six million postal votes.
A Conservative government would require voters to register individually on the electoral roll and show proof of identity.
Dr Fox said the government had failed to take action to improve electoral security "thanks to a turf war in Whitehall" between John Prescott, who is responsible for local elections, and Lord Falconer, who is in charge of national elections and referendums.
But a Labour party spokesman said: "The law on electoral fraud is the same law we had when the Tories were in power.
"They felt that law was adequate then and we do not see what has changed."
A Liberal Democrat spokeswoman said: "The government was thoroughly warned about the potential for abuse with the postal voting system.
"They should have headed those warnings and acted to prevent potential abuse before the general election."