Prime Minister David Cameron has called on Conservative Party supporters to "do everything" they can to ensure that voters reject a proposed change to Britain's electoral system.
On 5 May voters across the country will be asked if they wish to change the electoral system used at general elections from First Past The Post (FPTP) to Alternative Vote (AV).
The proposed change is favoured mainly by the Liberal Democrat Party, which is in a coalition government with Mr Cameron's Conservatives. The Conservatives are mostly in favour if keeping FPTP, while the Opposition Labour Party is split on the issue, although Labour leader Ed Miliband supports AV.
In an email to Conservative Party supporters Mr Cameron said, "It's clear that lots of people still haven't made up their minds - so we've got to keep on working to get the message out there that AV is an unfair, expensive and discredited system.
"This is not just about how we vote in General Elections. It's about how politics works, how governments are formed and ultimately, how our country is run."
The Prime Minister today spoke at "No to AV" event with former Labour Cabinet Minister John Reid. Meanwhile Ed Miliband at a "Yes to AV" event spoke in favour of a new voting system with Liberal Democrat Vincent Cable, who is currently the Business Secretary in Mr Cameron's government.
The referendum was one of the concessions granted to the Liberal Democrat's by the Conservative Party during negotiations to form a coalition after last year's general election.
Despite Liberal Democrat leader Nick Clegg being one of the key figures in getting a referendum, he has been in the background of the current campaign, with Mr Miliband refusing to share a platform with him on the grounds that Mr Clegg is too unpopular because of his alliance with the Conservatives and subsequent policy decisions on issues such as student tuition fees.