Nigel Farage faces an ‘imminent’ decision from a standards watchdog over whether he breached Westminster rules by not declaring a £5 million donation.

The Mail on Sunday understands that an inquiry into the undeclared gift from crypto-billionaire Christopher Harborne has now been completed – with sources predicting it will conclude that the Reform UK leader should have made it public.

If so, Mr Farage could be hit with a lengthy Commons suspension and even a second by-election in a few months.

However, that would spark a fierce backlash from Reform supporters, given that Mr Farage has claimed the donation was for his personal security and that he faced 300 threats a month.

On Friday, the alleged killer of former MP and Reform spokeswoman Ann Widdecombe was charged with preparing acts of terror against Mr Farage.

The Reform leader has previously insisted that he was under ‘no obligation’ to declare the gift, received in early 2024 before he became an MP, as it was given to pay for personal protection ‘so that I would be safe and secure for the rest of my life’.

He confirmed in April that he had received the money.

However, he was reported to the standards commissioner after both Labour and the Tories pointed out the MPs’ code of conduct states that new MPs ‘must register all their current financial interests, and any registrable benefits (other than earnings) received in the 12 months before their election’.

The Mail on Sunday understands the parliamentary standards watchdog has concluded its investigation into a £5million gift to Reform UK leader Nigel Farage

Mr Farage received the gift from businessman and crypto chief Christopher Harborne

Earlier this summer, Mr Farage sought to counter the standards inquiry and other allegations about not disclosing support from long-standing ally George Cottrell by resigning his Clacton seat.

Calling on local voters to be his judge, he said: ‘I have done nothing wrong. I have not broken the law in any way at all.’

After the other main political parties refused to field candidates against him, he was comprehensively re-elected.

However, after his return to the Commons, standards commissioner Daniel Greenberg promptly resumed his inquiry.

Sources claimed Mr Greenberg had completed his report and handed his conclusion – that Mr Farage should have declared the donation – to the standards committee, which will decide on any sanctions.

That raises the extraordinary prospect that if the committee imposes a Commons suspension of ten days or more, under special ‘recall’ provisions Mr Farage could face his second by-election in a matter of months.

However, some Westminster insiders suggested last night that both Labour and the Conservatives would prefer not to give the Reform UK leader another chance to appeal to his local electorate.

On Friday, Joshua Kerry, who is accused of murdering Ms Widdecombe in July, was charged with a terror plot against Mr Farage.

On BBC Radio 4’s Today programme on Saturday, Reform deputy leader Richard Tice spoke of his ‘deep shock’ at the latest allegations and said Ms Widdecombe’s death had made people take security more seriously.

He added: ‘What’s particularly upsetting for those around [Mr Farage] is sometimes he has not been believed, not been listened to.’

Mr Greenberg could not be reached for comment. Reform UK declined to comment.