Here is a profile of the five contenders in the running to replace Nigel Farage as leader of the UK Independence Party.
GERARD BATTEN MEP
A UKIP MEP for London since 2004, Gerard Batten reacted with fury to Nigel Farage's suggestion that Lord Pearson was the only "serious, credible" candidate for the party leadership, saying it was an "insult" to the other contenders and urging members to complain to the Electoral Reform Society. A former salesman for BT, Mr Batten was a founder member of the UK Independence Party and was its candidate for London mayor in 2008. He is a member of the European Parliament's sub committee on security and defence. If elected leader he has vowed to take the party forward by focusing on issues beyond withdrawal from the EU. He has also pledged to gain the party its first MPs at Westminster within five years.
MIKE NATRASS MEP
Former UKIP chairman and deputy leader, under Roger Knapman, and an MEP for the West Midlands since 2004, Mike Nattrass is one of the most experienced contenders in the race. He has laughed off Mr Farage's comments on the quality of the candidates and vowed to work with the current UKIP leader if elected, saying Farage's media skills are an asset to the party. A Yorkshireman and former chartered surveyor, who stood for the Referendum Party in the 1997 general election, Mr Nattrass has said fighting the next general election must be UKIP's top priority - and he has been particularly outspoken in his attacks on the Conservative Party's alleged betrayals over Europe. He also rejected moves towards the formation of a pan-European party, as some in the party have advocated.
LORD PEARSON OF RANNOCH
Identified by Nigel Farage as the only "serious, credible" contender to replace him as leader, Malcolm Pearson was one of two Conservative peers to defect to UKIP in 2007, giving the anti-EU party its first representation at Westminster. An old Etonian and chairman of a City insurance brokers, he hit the headlines earlier this year when he played host to controversial Dutch politician Geert Wilders. Lord Pearson has pledged to turn UKIP into a "harmonious, well-funded fighting machine". Says withdrawal from the EU must remain its core policy but has also made "standing up to Islamism" a key theme of his campaign and is also a keen advocate of Swiss-style direct democracy to hand "power to the people" through local referendums. Says UKIP can do well enough at the next general election to force a hung Parliament, which would help it bring about "radical change".
NIKKI SINCLAIRE MEP
One of two female UKIP MEPs to be elected this year, the very tall (reportedly 6ft 4ins) Ms Sinclaire has held many posts in the party over the years and has twice stood as a general election candidate. In a recent interview she described herself as "old UKIP" and said her ambition as an MEP was to "get rid of the EU, and make myself redundant". She has waged an energetic leadership campaign and if elected has vowed to professionalise UKIP's party structures, improve its communication with voters and introduce a shadow cabinet. She has also said she would appoint Nigel Farage as party spokesman to capitalise on his media skills.
He may be the least well known of the candidates, but Alan Wood holds a crucial role within the UKIP hierarchy - as the party's nominating officer, no one can become a candidate without his say so. A retired mechanical engineer, Mr Wood is a district councillor in Netheravon and chairman of Fittleton Parish Council, where he gained national coverage for a poll demanding an EU treaty referendum. He has been active in UKIP politics in the South West of England since 1996. In his leadership election address, he advocates forming alliances with other anti-EU parties, excluding the BNP, and talks of the need to transform UKIP from a pressure group to a "party fighting for government". He also takes a swipe at his better-known rival Lord Pearson, saying his stance on radical Islam would make the party unelectable and "lead us into the wilderness".