Nominations closing in UKIP leadership race
Nominations close later in the race to succeed Nigel Farage as UKIP leader.
Mr Farage, who led the party for most of the past eight years, stood down after the UK's vote to leave the EU.
Those vying to replace him include the party's immigration spokesman Steven Woolfe, councillor Lisa Duffy and MEPs Jonathan Arnott and Bill Etheridge.
Those wanting to stand need the backing of a proposer and 50 supporters from at least 10 UKIP branches. The winner will be announced on 15 September.
Nominations close at midday. The final list of candidates will be considered by the vetting committee of the party's national executive, before being announced on Tuesday, a UKIP spokesman said.
Only people who had been party members for at least five years could initially enter the contest, but this rule was later changed to set the minimum limit at two years.
Candidates must pay a £5,000 deposit to enter the contest, which will be refunded if they secure at least 5% of the vote.
Ms Duffy, a councillor in Cambridgeshire and a little known figure in Westminster, has the backing of UKIP's former deputy chairwoman Suzanne Evans, who wanted to stand herself but was unable to, having been suspended from the party following an internal dispute.
Mr Arnott, the North East's UKIP MEP, is a former general secretary of the party who was elected to the European Parliament in 2014.
Announcing his candidacy for the leadership earlier this month, Mr Arnott said he wanted to be a "strong and credible voice for the North East".
Mr Woolfe is thought to be Mr Farage's favoured successor and is seen as the frontrunner.
The 48-year-old barrister is a rising star in the party, holding the high-profile immigration and financial affairs brief, and one of UKIP's most accomplished media performers.
Mr Etheridge, the West Midlands MEP and Dudley councillor, has said UKIP should stick by its "core principles and values" and not be "distracted by negative influences".
The 46-year old was a Conservative activist before joining UKIP in 2011.
Mr Farage stood down following the UK's vote to leave the European Union, saying his "political ambition has been achieved".
He said at the time: "I want my life back, and it begins right now."
The face of Euroscepticism in the UK for nearly two decades, Mr Farage helped turn UKIP from a fringe party into the third biggest in UK politics - in terms of votes at the 2015 general election.
He also helped persuade more than 17 million people to vote to leave the EU.
He also stood down briefly as leader in 2009, but was re-elected the following year.
He said he would quit after failing to win his seat at the 2015 general election, but stayed on after the party rejected his resignation.