Mr Hookem has long been a figure of note in Ukip after being called up to serve as the party’s defence spokesperson in 2014 by Nigel Farage – while Mr Kurten is hotly tipped as a future leader.
Local Government spokesperson Tim Aker followed suit, saying he “cannot continue to serve under Henry Bolton”.
Now their resignations are added to a list that is steadily racking up against Henry Bolton, who refused to step down yesterday despite receiving a unanimous vote of no-confidence from the party’s NEC.
Despite today’s resignations the embattled Ukip leader is reportedly adamant on staying in place – and has vowed to make new appointments to replace those who step aside.
In a statement Mr Hookem said: “Although I did not make it public at the time, I resigned my position as Assistant Deputy Leader of UKIP on Friday morning, both verbally and in writing.
“I kept this private, as I had no intention of pre-empting the decision of the NEC and also to give Mr Bolton the opportunity to do the honourable thing and resign.
Mike Hookem has long been a senior figure in the party
“Rather than media reports being focused on the hard work of the party and our members in fighting for Brexit, the story has become about the leader’s personal life.
“This is unfair to all those who have put so much time, effort and money into our party.
“Therefore, following the NEC’s meeting and their vote of no confidence in our leader, I now urge Mr Bolton to stand down as a matter of priority, for the good of the party and the grassroots membership.
“This would give Mr Bolton a chance to deal with his personal life, away from the media glare; and for UKIP to get back to its aim of fighting for a real Brexit.”
In a statement posted to Twitter, Mr Kurten added: “I have written to Henry Bolton and resigned as UKIP Education and Apprenticeships Spokesman.
“It is time for him to step down with dignity rather than extending the current debacle for another four weeks.
“I will continue to represent the party in the London Assembly”.
The resignations follow the revelation Bolton had started a relationship with Marney, 25
Their resignations follows Ukip official John Bickley, who quit as the party’s immigration spokesman in protest.
Ukip’s Deputy Leader Margot Parker has also stepped down along with the party’s Brexit spokesman Gerard Batten over what he branded the “Henry Bolton fiasco”.
Mr Bolton announced on January 15 he had ended his relationship with 25-year-old glamour model girlfriend Jo Marney in a bid to save his job.
However he was seen shortly afterwards meeting with the young model in London.
Jo Marney allegedly referred in text messages to Prince Harry’s fiancée Meghan Markle as a “dumb little commoner” with a “tiny brain” whose “seed” would “taint the Royal Family”.
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Ms Marney also described Meghan Markle as “a scrubber” and a “gender equality ****” who is “obsessed with race”.
In a statement following the revelation, Ms Marney said: “I apologise unreservedly for the shocking language I used. The opinions I expressed were deliberately exaggerated in order to make a point and have, to an extent, been taken out of context. Yet I fully recognise the offence they have caused.
“No offence was intended and, again, I apologise unreservedly for any such offence or hurt that my messages have caused to members of the public, members of Ukip my friends, family and loved ones.
“I have disappointed them all and let myself down. I cannot sufficiently express my regret and sadness at having done so.”
Marney, who has worked as a glamour model, allegedly made derogatory statements about Meghan Markle
The news has sparked speculation Nigel Farage could return to the top job, having stepped down in 2016 following the historic Brexit vote.
But speaking to Express.co.uk, the MEP and radio host insisted he had no interest in replacing Mr Bolton.
He simply said “no” when asked if he was tempted to return to the leadership.
However, allies of Mr Farage believe that he could join a party dubbed “Ukip 2.0” if Mr Bolton was removed from his position.
Reports suggest the new party would be chaired by Ukip donor Arron Banks while Mr Farage could become president.