Even Nigel Farage's fiercest critics admit he is a formidable presence in Ukip.
The eurosceptic leader has repeatedly mused about how long he may last at the Ukip helm, and last year suggested that 2015 is the last general election he will fight as Ukip leader. "By 2020 I will be too old and knackered and we’ll have found somebody else," he told the Express and Star.
But what would happen if Farage quit as leader, or was deposed in a party coup?
The pressure has been intense on the Ukip leader over recent days. He had to suffer the defection of Amjad Bashir, the party's leading Asian figure, to the Tories, as well as his health spokeswoman slapping him down after he called for a renewed debate on the NHS' future. On top of this, minutes were leaked from the party's national executive showed how senior Ukip members considered backing a privately-run form of the National Health Service, and also debated how to sort out their policies.
Given the significance of Farage's departure, as a milestone in the party's history, HuffPost UK has asked Ukip insiders and experts to look to the future.
"Nigel Is Unassailable...Until He Starts Losing A Few Battles"
"While Ukip do well electorally, Nigel is of course unassailable," said Godfrey Bloom, a Ukip MEP from 2004-2014 who used to share a flat with Farage in Brussels, "as of course was Napoleon."
"When Napoleon was winning battles, he wasn't going to be shifted, but when you start losing a few battles, it won't be quite so straightforward."
Critics, and supporters, are near unanimous about Farage being influential in the party. "The reason Ukip is the way it was is because of Nigel," one long-standing member remarked. "He put us on the map."
Another recalled the hiatus Farage had in his leadership when he stood down in order to fight the seat of Buckingham, with Lord Pearson taking over the reins from 2009-2010 while he took the position of chief spokesman.
"Farage was the real leader during that period," he said. "No-one was in any doubt."
One colleague describes him "as an enormous character", adding: "My respect for him has grown due the amount of work he has had to do."
Others are less warm about Farage's influence, like his former deputy David Campbell-Bannerman, now a Tory MEP, who insisted that the party was a "one-man band and a bit of a cult" in Farage's favour, while MEP Marta Andreasen hit out at his "Stalinist" leadership style before also leaving to join the Tories.
Given Farage's importance in Ukip, how could his leadership come to an end? Dr Rob Ford, a political scientist at Manchester University and co-author of "Revolt on the Right", suggests three possible ends: retiring on a high after many years at the top, stepping down due to ill health, or the "less likely" option of jumping ship to avoid having to deal with a massive crisis.
The pressure on Farage at the top is immense, as he not only has to keep the party together but to survive a seemingly constant stream of negative headlines and damaging leaks by enemies, but also has to cope with the injuries he suffered in an air crash in 2010, which are said to have caused him "agonising pain".
"Farage's role is important because he keeps the show on the road," Dr Ford said. "You do need some pretty impressive organisational skills to keep often very fractious and difficult people marching behind the same banner, and I think he is tremendously effective at that. You don't see this so much because it's internal, private and so on.
"One of the biggest challenges for Ukip in a post-Farage era will be maintaining internal unity. They have form on that, having nearly split up on several occasions in their 20 year history and Farage was a key figure in preventing a split from occurring on at least two of those occasions."
Many accuse Farage of being too controlling. In an example of Farage's grip on the party machinery, Bloom, who represented Yorkshire and the Humber, claims that the party's ruling executive has the power to overturn any vote by the members.
"We've got around 40,000 members, I shouldn't think about 100 understand the new constitution," he said. "We could all vote 100% in favour of whatever it happens to be and it can be overturned by Nigel, which is why Yorkshire has no representation on the NEC [National Executive Committee], we were considered the awkward squad.
"There is a whole mafioso at Brooks Mews [Ukip's HQ in Mayfair, London] who are personally beholden to Nigel for their salary as are most Ukip MEPs," he went on. "Someone said to me the other day, the power head office have now is something the Stasi would only dream of! The whole point of Ukip is it is supposed to be different."
Some veteran members have been concerned about Farage's focus on immigration as party leader in order to get ahead politically, at the expense of the party's radical "small government" ethos.
One senior figure complained: "Since Nigel decided it'd be more electorally successful if we zeroed in on one subject, which is immigration, and so far that has been proved correct. He has majored on immigration, which a number of the founding members are uncomfortable with it.
"Nigel has dumbed the party down. The professional classes are leaving. Immigration has brought a different sort of member, a different sort of activist, if you look at Facebook, you see the effects of the dumbing down of the membership, the language, the spelling. All these things on social media are a sign of it.
"The Sensible Contenders Are Keeping Focussed On The Campaign"
Farage's entrenched position in the party means that few would directly challenge him for the leadership, so rising stars will be careful about how they position themselves.
"Most of them are being sensible and keeping focussed on the campaign," an insider remarked. "While Nigel remains a successful leader, they'll be behind him."
Dr Alan Sked, founder of Ukip and its first leader, said: "Douglas Carswell might offer a focus for opposition [to Farage] within the party. However, he has already shown he lacks the backbone to confront him and has the charisma of a wet turd."
As a result, any aspiring successors will wait until Farage leaves the stage. But is the party ready for that?
Dr Ford suggests that Ukip lacks an obvious figure of Farage's authority to hold the party together after he goes. "How do you keep people like Douglas Carswell, [donor] Stuart Wheeler, [deputy leader] Paul Nuttall and [economics spokesman] Patrick O'Flynn all on the same page? None of them are necessarily people who much like taking direction anyway," he said.
"Everyone in the party recognises Farage's authority and defers to it. It's not clear yet whether there's a another figure who could do that. Without Farage we'd likely see an awful lot more arguments out in the open."
The Ukip leader has been trying to build up his top team, so one day, they may have the profile to fill the void. "Farage wants there to be a clearly identified second tier who people have heard of," Dr Ford said.
Farage's departure would pave the way for Ukip's top brass to make known if they want to step up and succeed him. The Ukip leader has not hinted at who he would want as a successor, beyond last year speculating that it was "more likely.. [to be].. a woman next than [for] any party.
Party insiders don't hide the scale of the challenge "I think there'd genuinely be a period of saying 'Gosh, he's gone...!'," one senior Ukip member admitted. "There would definitely be a period of when we would have to answer two questions: 'What next? And how do we do it?'
Some, like Ukip deputy leader Paul Nuttall and migration spokesman Steven Woolfe, have already put themselves forward as possible candidates to succeed Farage.
Other senior Ukippers are thought to be possible contenders to take over from Farage, like Douglas Carswell, who has proudly spoken of the need for the party to be "internationalist".
He has played down suggestions that he could be a future leadership contender, telling Buzzfeed: "I’m not one of UKIP’s major players".
Some insiders are sceptical about Carswell's apparent modesty, with one figure arguing that he is "defining himself so people know what they'd get if he was leader."
"Whenever I see Carswell do an interview, I think his views are so at odds with his party, why is he in it?," Dr Ford said.
"If you want to shape the message, then there's an obvious position to do it from isn't there? I do wonder if his protestations of disinterest might change."
Will It Be "Nukip" vs "Pinko" Ukip vs Libertarian Ukip?
Assuming the rumoured candidates are interested in succeeding Farage, figures like Carswell and Woolfe are likely to offer a modernising 'new Ukip' (christened "NUkip") that stresses the party's free trade, liberal credentials and strikes a softer tone towards migrants.
Woolfe has given a sense of this after telling HuffPost UK how Farage has recently "adopted a more nuanced tone" since he took on the migration brief, adding: "He [Farage] has clearly stated recently about the need to have an ethical migration policy."
Others like Patrick O'Flynn would offer a "Red Ukip", having infamously drew his leader's ire by floating a "Wag tax" on luxury goods. He recently was recorded admitting to a split in the party, as he hit out against his right-wing libertarian colleagues.
Ukip MEP Patrick O'Flynn, self-described "pragmatist" in the party
"Sometimes I put things at the limit for some of that libertarian wing of the party," he said. "And they can sometimes regard me as a bit of a leftie. I think I was called 'Pinko Patrick'. I'm a pragmatist on this stuff I personally I think the flat tax was simply too right-wing."
Not everyone would feel sympathy for O'Flynn's stance. Arron Banks, the Ukip supporter who is financing the party's election campaign with a £1m donation, told the Financial Times recently hat he did not like "pinkos".
Meanwhile, other MEPs, like Scotland's David Coburn, have prided themselves on their libertarian credentials. Coburn recently stoked controversy after accusing Labour and the Liberal Democrat "equality Nazis" of wanting to outlaw sex.
If Nigel Left Ukip, Would Ukip Leave Nigel?
Leaving such an opinionated group behind, how would Farage cope with moving on? Some suggest that he may leave as leader, but will find a way to keep his influence in the party. "He would run things from behind the scenes before staging a comeback," one Farage supporter predicts.
Woolfe told HuffPost UK that he hoped Farage could stay on as "executive chairman" as the party would need "his guidance and wisdom".
Others suggest he would be more relaxed. One veteran member remarks acidly: "As long as he's got his MEP's pension, he's not bothered."
Bloom suggests that Farage would be tempted by any job offer that paid well, but his business opportunities may be limited.
"Over the last 20 years, Nigel often made fairly cryptic comments about Ukip which would lead me in retrospect to expect that if something turned up which held more financial or prestigious appeal, he would quickly move on with no great backward glance.
"It'd be very difficult to go back into the City though, because the natural course would be working as a non-executive director of a City company. Nigel doesn't have that background. He was a trader, which were not considered particularly smart in the City."
Bloom suggests that Farage would lack the contacts of having been in government, adding: "Nigel wouldn't be offered a City role and there is only one thing that could interested him or suit, so it's not available."
The ex-Ukip MEP's insight into Farage is especially significant as he has known him since the early days of Ukip. He has a surprising diagnosis for Farage's anxiety to make money and succeed - his desire to be "accepted by the establishment" that he publicly claims to loathe.
"Unlike his public persona, he is very impressionable, defensive about his lack of traditional education and, believe it or not, racked with self doubt. I think this accounts for his reluctance to surround himself with alpha males.
"There are no alpha males left in Ukip, Nigel has left all the alpha males. they're all beta, some of them very charming, but they are beta males, Nigel is very uncomfortable who can take the spotlight or even the intellectual or moral high ground.
"Much has been made of his supposed desire to get into the House of Lords but I would not discount it, nor would I discount his wife's ambition. All this is difficult to comprehend for those comfortable in their own skin socially or professionally. Acceptance by the establishment is probably a stronger driving force than we perhaps imagine."
Dr Sked, who worked with Farage in the early days of Ukip in the 1990s, argues that he would remain an MEP "collecting what he could in salary and expenses in Brussels".
"He has no shame and no ability to do anything else in life. He couldn't go into the City - he was only an unsuccessful commodity broker," he adds.
Another suggests that Farage could build on his profile in Ukip to blaze a trail as a media commentator. "He has worked incredibly hard and still works very hard," one insider insists. "If he stopped being leader, I think he'd properly stop and maybe go work as a political commentator."
Farage has already built up a significant profile in Ukip, with regular columns in the Independent and Daily Express newspapers, so a media career isn't hard to envisage.
The question is how long the People's Army will want to march without general Nigel at the helm.