Ukip is sliding into an all-out civil war over whether Nigel Farage should be its leader

Briefings and anonymous counter-briefings have dominated the general election aftermath

Ukip is sliding into all-out civil war over whether Nigel Farage should remain its leader after he made an unexpectedly swift return to the post.

Party donor Stuart Wheeler told BBC Radio 5Live that Mr Farage should resign and be subject to a full leadership election rather than simply returning without challenge.

Senior sources also reportedly told the Press Association news agency and BBC News that the party leader should "take a break" and have to stand for re-election, respectively.

The demand comes after Ukip’s economics spokesperson Patrick O’Flynn told The Times newspaper that Mr Farage had transformed into a “snarling, thin-skinned, aggressive” man after the election.

Mr Farage stepped down as leader, as pledged, after he lost the race to become the MP for Thanet South.

But after presenting his resignation to Ukip’s national executive he was apparently rebuffed and told to remain as leader.

The decision seems to have angered critics of Mr Farage, who have have piled in. Godfrey Bloom, a former MEP who left the party last year, told BBC News that the leader was “capable of some abrasive behaviour” and “not a team player”.

He went on to endorse the party’s only MP, Douglas Carswell, as leader. Mr Carswell has previously ruled himself out of any leadership bid.

But the group around Mr Farage's inner circle has been quick to hit back at critics.

This morning sources close to Mr Farage briefed journalists with highly personal attacks against Mr O’Flynn, telling The Spectator magazine that the economics spokesperson has “personal problems and this may be the manifestation of them”.

After the briefing came to light Mr O’Flynn told Sky News that Mr Farage was his “political hero”, in an apparent change of rhetoric.

“If anyone thinks or supposes that I’m planning some kind of coup again Nigel they couldn’t be more wrong. He is my political hero and will remain so,” he told the channel.

He went one to criticise “a couple of people in [the leader’s] inner circle, to use a term, who are wrong-uns” and said Mr Farage should never have pledged to stand down as leader.

Ukip's director Steven Stanbury appeared on the BBC's Daily Politics programme this afternoon and called for the party to conduct itself more professionally.

“The four million who voted for us ... expect a more professional approach and not the selfish, self-indulgent attacks that we are seeing,” he said.

Ukip achieved a record vote share in the general election last week but ended up with fewer MPs than it went into the contest with.

Nigel Farage failed to win his target constituency of Thanet South after a hard-fought contest, with only Douglas Carswell, a former Conservative defector, retaining his seat.