The general election is to be held on 5 May. Key questions about how an election works are answered below.
WHAT ARE WE VOTING FOR?
The general election will decide which party (or coalition of parties) forms the next government. There will be 646 seats in the UK Parliament's House of Commons up for grabs - down from the current 659 because of changes to constituency boundaries.
WHEN IS THE ELECTION?
Tony Blair has announced 5 May as polling day. The last poll was 7 June 2001, with the new parliament sitting later that month. An elected parliament lasts no longer than five years, therefore this last parliament could have continued until late June 2006. An election campaign takes about four weeks, so the election could have been held in July 2006. Votes are traditionally held on Thursday, but do not have to be. Elections cannot be held on weekends or public holidays.
HOW DOES THE VOTING SYSTEM WORK?
The UK uses a First Past the Post system. To become an MP, a candidate simply has to win more votes than any rival in their constituency, not a majority of votes cast. Critics claim this means many people's votes are "wasted" and want some kind of proportional representation, where the national share of the vote determines the number of MPs.
WHAT HAPPENS IF THE PRIME MINISTER LOSES HIS SEAT?
His party would offer up a candidate, probably the deputy prime minister, to hold the reins temporarily as a caretaker leader/prime minister. The Queen would then call the potential prime minister to Buckingham Palace to ask him whether he would form a government. The governing party would then hold a leadership election.
WHO CAN VOTE?
You must be registered to vote, be at least 18-years-old on polling day, be British or be a Commonwealth or Republic of Ireland citizen living in the UK.
WHO IS BANNED FROM VOTING?
The following are barred from voting in general elections: members of the House of Lords; convicted prisoners; anybody found guilty of election corruption within the last five years; people with learning disabilities or a mental illness who are incapable of making a reasoned judgement.
HOW DO I REGISTER TO VOTE?
It is now too late to register for this election. You can check whether you are on the electoral roll by contacting the electoral services department at your local council. Their contact details are listed on the Electoral Commission's special website.
HOW DO I VOTE?
Those registered to vote should be sent a polling card about a week before the election, naming your polling station. You should take the card with you to vote, although it is not compulsory and other identification can be accepted.
WHAT IS ON THE BALLOT PAPER?
You will be given an officially marked ballot paper listing all the candidates in alphabetical order of surname, with the description of their party, if they have one. You place an X in the box beside your one chosen candidate.
CAN I VOTE BY POST?
Yes. The general election is not an all-postal vote like the trials held in some regions last year but you can ask for a postal vote from the electoral services department at your local council - whom you should also contact if your polling card fails to arrive. If you apply for a postal vote and then decide you would like to vote in person after all, you must take the whole of your postal voting package to the polling station in order to vote.
WHAT ABOUT PROXY VOTES?
Voting by proxy - getting somebody else to vote for you - is allowed if you can satisfy the local electoral registration officer you cannot vote, perhaps because of work, study, holiday, illness, or because you have moved house since registering to vote. The deadline for applying is 26 April.
IF I LIVE OVERSEAS, CAN I STILL VOTE?
You can register as an overseas voter if you are a British citizen and have been on a UK electoral register at any time within the past 15 years. To do so, you must be registered in the local authority area where you wish to vote - although it is now too late to do this for this election.
IS VOTING COMPULSORY?
No, people cannot be forced to vote, nor is registration itself compulsory. But those failing to return a completed registration form or giving false information can be fined up to £1,000.
WHAT HELP IS THERE FOR DISABLED VOTERS?
To help blind and partially-sighted voters, there has to be a "tactile device" in each polling station and there are rules on the size of print on ballot papers. The vast majority of poling stations are now more accessible for wheelchair users. Proxy ballots are allowed for those unable to vote because of disability, but they will need a doctor's certificate.
WHAT HAPPENS IF A VOTER IS ILLITERATE
There is no literacy qualification for voting: anyone who is illiterate can ask the polling officer at the polling station to mark their ballot, or take a companion to help them.
IS MY VOTE SECRET?
The ballot papers contains a serial number: it is possible, but illegal, to trace all the votes to the people who cast them. The number is there to stop electoral fraud.
WHO CAN STAND AS A CANDIDATE?
Candidates must be aged 21 or above and be British, Commonwealth or Republic of Ireland citizen. Those banned for standing in general elections are: bankrupts; civil servants; police officers; armed forces personnel; government-nominated directors of commercial companies; judges; members of parliament in non-Commonwealth nations; those convicted of electoral malpractice; members of the House of Lords.
HOW CAN I BECOME A CANDIDATE?
To be a candidate, you need to have a nomination form signed by 10 voters from that constituency. The papers must be returned by 19 April, along with a £500 deposit. Candidates do not need to be a member of a political party. The main parties have their own selection methods, usually involving central lists of candidates and votes of local members.
HOW CAN I SET UP A POLITICAL PARTY?
All political parties have to be registered with the Electoral Commission, a process which costs £150. The commission will need the names of three party officials and details of the party's financial schemes. It can decide to refuse to register a party if its name is confusingly similar to another party's or if the name is offensive in some way.
CAN CANDIDATES SPEND AS MUCH AS THEY WANT ON CAMPAIGNING?
No, there are strict limits on what is spent once nominations close on 19 April. Each candidate has to account for their election expenses after the poll. Candidates in rural (county council) areas can spend up to £7,150 plus 7p per elector. Those standing in urban (borough council) areas can spend £7,150 plus 5p per voter.
HOW MUCH CAN THE PARTIES SPEND?
Registered parties are restricted in their spending for the 365 days before the election. Parties can spend up to £30,000 for each seat they contest - which adds up to £19,380,000 if they fight every constituency. They are also permitted to have spent another £3.51m on their European elections campaigns last year - provided they had candidates in every region.
WHERE DOES THEIR MONEY COME FROM?
Political parties and candidates raise funds in a variety of ways from subscriptions to local fetes and dinners. There are strict rules on donations: those of more than £200 to a party or £50 to a candidate have to be from permissible donors - effectively banning overseas gifts. All donations of more than £5,000 to a party, or £1,000 to a local branch, have to be publicly declared.
IS THERE ANYTHING TO PREVENT THIRD PARTIES SPENDING EXTRA MONEY BACKING POLITICAL PARTIES' CAMPAIGNS?
Yes, people or groups campaigning on behalf of one or more political parties or candidates who advocate a particular policy, face limits too. They can spend up to £10,000 in England and £5,000 in each of Scotland, Wales and Northern Ireland. The groups also must pass the same tests which apply to political donors.
HOW CAN I FIND OUT WHAT A CANDIDATE OR PARTY BELIEVES?
Each party should publish an election manifesto which is available from them or can be bought in the shops. Candidates will campaign locally and are entitled to one free mailing of an election leaflet to voters in their constituency.
WHO ORGANISES THE ELECTION?
The top civil servant of the local council is the returning officer for each constituency, with the day-to-day running of the poll left to the head of the council's electoral services department.
HOW MUCH DOES IT COST TO RUN AN ELECTION?
The last general election, in 2001, cost £80m to organise.
ARE THERE RULES FOR THE BBC'S COVERAGE?
Yes, every part of the BBC has to follow the guidelines set down by the corporation's governors. They include advice on the "appropriate" level of coverage to give the main parties and how to reflect the smaller ones such as UKIP, the Greens, the SNP and Plaid Cymru.
WHY ARE ELECTIONS HELD ON THURSDAYS?
They do not have to be - it is just a convention. One theory about its origins is that people were not paid until Fridays and so holding polls on Thursdays ensured they were not too drunk to vote. The Electoral Commission has recommended trials of weekend voting as a way of improving turnout.