The race to replace Nigel Farage was thrown into confusion after the frontrunner for Ukip's crown missed the nominations deadline.
MEP Steven Woolfe insists he is still in the contest, but the party made it clear no final decision would come until the completion of vetting procedures on Tuesday.
Woolfe claimed "technical" issues with the party's system caused the problem which meant he overshot the noon Sunday deadline by 17 minutes.
The MEP said Ukip officials were kept fully aware of the problems, but a party spokesman would not be drawn on the issue, stating only: "Nominations have been received. Vetting will take place over the next few days. It must be understood that Ukip cannot comment on the process."
The cautious tone was in marked contrast to the MEP's spokesman who insisted Woolfe was still in the competition.
"Steven Woolfe remains a candidate in the Ukip leadership contest. He submitted his application form at 11.35am this morning, in advance of the midday deadline.
"However, due to technical problems on the party system, it did not successfully go through until 12.17pm.
"Mr Woolfe was speaking to party officials responsible for handling the application process throughout this time and right up to the deadline.
"He informed them that he was having technical problems. These problems were resolved and the paperwork submitted," the spokesman said.
The comments followed claims on social media that Woolfe had been disqualified from the race due to missing the deadline.
I have had it confirmed that Steven Woolfe has been told his nomination for Ukip leader was disqualified as it arrived beyond noon deadline
-- Michael Crick (@MichaelLCrick) July 31, 2016
Before the nomination controversy, Woolfe faced allegations he allowed his membership to lapse for more than a year which raised issues about his eligibility under controversial new party rules.
Woolfe, the party's immigration policy chief had been favourite to take over, but councillor Lisa Duffy and MEPs Bill Etheridge and Jonathan Arnott have also been pushing for the crown.
Huntingdonshire councillor Duffy has pledged to heal factional fighting in the party.
She is backed by former deputy chairwoman Suzanne Evans, who was suspended from the party earlier this year after repeated clashes with Farage.
Farage announced he was quitting after the narrow Leave victory in the EU referendum, saying: "I want my life back, and it begins right now."