The BBC has been speaking to people in Clacton, the constituency at the heart of this by-election, about Farage's announcement today.

“I'm very disappointed because [Farage] promised all these things and he's gone back on his promise,” one woman says.

She adds: “Who can you trust in the government nowadays? You can't trust Labour, you know. We can't trust the Conservatives and now we can't even trust Reform, so I really don't know who I'd vote next time.”

One man says: “I'm absolutely gutted. I thought he was going to run the country and everything was going to be lovely. Don't know what to say other than that.”

Predicting by-election results can be a dangerous gamepublished at 16:12 BST

16:12 BST

Joe Pike
Political correspondent

Image source, PA Media

Nigel Farage is triggering a by-election to shore up his position and, as he said in his speech, to "continue the political revolution that Reform has started".

But his critics argue it is a stunt to distract from questions over his personal finances, and ultimately taxpayers will be forced to pick up the bill of holding a vote.

The Reform leader says "the people of Clacton should be the judges of my actions", but there is no sign the party's four MPs who defected from the Conservatives will follow suit and let their constituents decide whether to keep them.

And for all Farage's talk of the importance of private sector experience in politics and having "leaders who know how to make money" (and many across the political spectrum agree with him), it is not money he has earned that has made headlines.

Instead it is the gifts and gifts-in-kind he received before entering parliament that journalists and Parliament's standards commissioner are assessing.

Nigel Farage won the Clacton seat in 2024 with a majority of 8,405 and 46% of the vote. His party's dominance in national opinion polls means he goes into this contest as the favourite.

But British politics has changed a lot in recent months, including the rise of Rupert Lowe's right-wing party Restore. What of Kemi Badenoch's Conservatives, who used to hold the seat? And will Andy Burnham's likely leadership of Labour give that party a bounce?

Predicting by-election results can be a dangerous game.

Reform wants this by-election to happen quicklypublished at 16:06 BST

16:06 BST

Chris Mason
Political editor, reporting from the Nato summit

Senior Reform sources are making it clear they want the by-election to happen as soon as possible - and will crack on with the parliamentary formalities to do so quickly.

This will mean Nigel Farage being given a Crown appointment which bars him from being an MP - either Crown Steward and Bailiff of the Chiltern Hundreds, or Crown Steward and Bailiff of the Manor of Northstead.

Once this has happened and the Clacton seat is vacant, the writ can be moved in the Commons to trigger a by-election.

Image source, PA Media

Conservative leader Kemi Badenoch says Nigel Farage is "cracking under the pressure" because "he is finally having to face some scrutiny".

But she won't say if her party will contest the Clacton by-election sparked by his resignation.

Speaking at a Politico Playbook live event, she says the by-election will be a "waste of taxpayers' money", and suggests there could end up being two in the Essex seat, if the parliamentary standards commissioner finds against Farage in its investigation.

She suggests there shouldn't be a by-election while the investigation continues, adding that the Tories are exploring "every avenue".

Chris Mason
Political editor, reporting from the Nato summit

Speaking to reporters at the Nato Summit in Ankara, Prime Minister Keir Starmer says:

"This is a desperate stunt from Nigel Farage and it's obvious why he's doing it - he is up to his neck in sleaze.

"Politics should be about improving the lives of millions of people, not about personal gain, not about hiding dodgy donations, and I think the public will see this for exactly what it is."

Image source, POOL

Nigel Farage has said Reform is willing to cover the cost of the Clacton by-election.

"I have spoken to the CEO of Tendring District Council," he posts on X. "Reform has offered to cover the cost of the by-election.

"I will be writing to Rachel Reeves later today with the same message.

"Given that we asked for this by-election in the first place, it’s only right that we pay for it."

It is unclear if the offer would be accepted, or even could be.

Farage's comments follow earlier remarks from Liberal Democrat leader Ed Davey, who called for the Reform leader to cover the cost of running the by-election.

Image source, PA Media

We're now hearing from a spokesperson for Andy Burnham, who is widely expected to replace Keir Starmer as prime minister.

The spokesperson describes the Reform UK leader's resignation as a "gimmick designed to distract from serious allegations about Farage's funders".

"What really matters in politics is how we can change Westminster to take power for communities and bring it back to people to make life more affordable for them," the spokesperson adds.

By-election expected to take place next monthpublished at 15:36 BST

15:36 BST

Chris Mason
Political editor, reporting from the Nato summit

Hello from the Turkish capital Ankara. I am part of the reporter pack covering the prime minister’s trip to the Nato summit getting under way here.

Nigel Farage — as so often in the last couple of years — has managed to upstage Sir Keir Starmer again, albeit via what his critics see as a self-serving stunt.

Speaking to his allies this afternoon, his aim here is to clearly frame this as “the people versus the establishment”, as one friend put it.

“This is Nigel setting the agenda, he is sick to death of being judged by Sky, The Times and Daniel Greenberg,” they added, the latter a reference to the Parliamentary Commissioner for Standards.

They intend, I am told, to move the writ for the by-election as soon as they can — while parliament is sitting and before its summer break, beginning in a few weeks.

That would likely mean a by-election at some point next month, just as a new government led by Andy Burnham is beginning its time in power, in all likelihood.

The question now is how Reform’s opponents react. Do they put up candidates or not? Reform is baiting Labour to do so, claiming it would be Burnham’s first big test.

But there is precedent in these situations for opponents not to bother — and to argue they are not going to endorse what they see as a publicity stunt by taking part.

It is worth remembering that this by election doesn’t end the investigation that the Standards Commissioner is conducting, which could itself eventually lead to what is known as a recall petition and, yes, a by-election.

But Reform are effectively trying to say we are getting ahead of you — and who would want repeated by elections? A subsequent by-election would only happen in that scenario if enough folk in Clacton wanted one.

Constituents in Clacton are used to political attentionpublished at 15:30 BST

15:30 BST

Simon Dedman
BBC Essex political reporter, in Clacton

This is going to be a big shock and bolt out of the blue here in a very hot and sunny Clacton.

However, the people here are not completely unused to having the media and all the political parties descending on this seaside town.

Twelve years ago there was a massive Westminster by-election, when Douglas Carswell quit the Conservatives and stood for UKIP - the party that Nigel Farage then led.

Clacton became an epicentre during the EU Referendum campaign and was a bastion of the Leave vote.

Then Nigel Farage decided to come back and try again for Westminster two years ago and also put Clacton back on the political map.

Image source, EPA/Shutterstock

Liberal Democrat leader Sir Ed Davey calls for Nigel Farage to fund the Clacton by-election himself.

He says: "Nigel Farage has spent his whole life dodging responsibility for his actions. This new stunt is his latest attempt to escape consequences for his biggest grift."

Davey says the Reform leader has "done nothing for his constituents" and the people of Clacton "deserve better".

“It would be a crime to waste taxpayers’ hard-earned cash on this Farage vanity project.

"He should pay for it himself out of the millions he’s grifted.”

Joe Pike
Political correspondent

Nigel Farage will be contesting the Clacton seat 30 years after he first stood in a by-election. In Eastleigh in 1994, he stood for UKIP and came fourth behind the Liberal Democrats, Labour and the Conservatives.

This will be the ninth time Farage has fought a Westminster seat: he lost seven times before his victory in Clacton in 2024.

Brian Wheeler
Reporting from Westminster

Nigel Farage’s arch rival Rupert Lowe wastes no time in attacking the Reform UK leader’s by-election announcement.

Lowe formed his own party, Restore Britain, after a spectacular falling out with Farage and is proving to be a persistent thorn in Reform’s side.

In a post on X, Lowe says: "The people of Clacton do not need a media circus descending on their town over a busy tourist season because their MP has made a series of bad decisions.

"He should have declared that five million pounds. He knows it. We all know it. Now he is going to weaponise a by-election to distract from that."

Lowe adds: "I will be making an announcement later today about Restore Britain’s plans for the Clacton by-election."

Image source, PA Media

Green Party leader Zack Polanski has responded to Farage's announcement, arguing the Reform UK leader "is a grifter".

In a post on X, he says Farage "knew he was heading towards a by-election anyway so has pulled the trigger early".

Polanski adds: "The people Vs the establishment?! Reform are literally part of the establishment."

The Parliamentary Commissioner for Standards opened an investigation into the Reform UK leader in May, for allegedly failing to properly declare a £5m donation. The commissioner can refer a case to the Commons' Standards Committee, which can trigger a by-election in an MP's constituency.

Watch for response from Reform's rivalspublished at 14:57 BST

14:57 BST

Chris Mason
Political editor

What's going to be really interesting in terms of the coming battle is the response of Reform's rivals.

If we rewind the clock at 18 years, Conservative MP David Davis voluntarily triggered a by-election in his constituency over an argument that he was making about civil liberties, which he felt were being trodden on by the then Labour government.

That decision took quite a lot of Conservatives by surprise and plenty of the big other parties didn't contest that by-election.

They didn't want to play into the self-delivery of theatre, as they saw it, that Davis chose to engineer.

So let's see, the best part of two decades on, how the Conservatives and Labour and others choose to approach this.

Farage is framing by-election as the people v the establishmentpublished at 14:51 BST

14:51 BST

Chris Mason
Political editor

That's how Nigel Farage is trying to seize the initiative and the momentum, if you like, of having his back against the wall with all of the revelations relating to his finances.

On top of that, you could hear the anger - and it is authentic anger - about what he sees as the unreasonable encroachment on his family as a result of the swirl of media attention.

We were several steps from it, but a by-election was already being talked about at Westminster as one potential outcome of the investigation under way by the parliamentary standards commissioner into Farage's £5m gift.

One scenario down the track after the investigation's findings were released could have been a recall petition and potentially a by-election.

We've seen that in the past where MPs find themselves in that situation against their will.

Here is Nigel Farage seizing the moment and the initiative and saying that he'll press ahead with that by-election and framing it, as he so often does, as a tussle between the people and elements of the establishment.

Investigations into Farage would begin again if he wins by-electionpublished at 14:41 BST

14:41 BST

Henry Zeffman
Chief political correspondent

It is worth stating that if Nigel Farage were to win this Clacton by-election, investigations into him will resume. That is what Parliament's rules are.

So Farage isn't forcing this by-election in order to stop that investigation ever happening, he is doing it in order to appeal to a higher political authority than the House of Commons standards commissioner.

He is arguing: "I derive my mandate from the voters of Clacton."

It is a bold political gambit, and it could well determine the question of who has the opportunity to become Britain's prime minister at the next general election.

A very significant announcementpublished at 14:35 BST

14:35 BST

Henry Zeffman
Chief political correspondent

That is a very, very significant announcement.

Nigel Farage will very shortly no longer be an MP, but he intends to continue in his role by asking his constituency to re-elect him.

After many failed attempts, Clacton made Farage a Member of Parliament in the 2024 general election.

Farage's statement has now finished - but we're still working through the details and will bring you analysis on his announcement.

Stay with us.

Farage says he "will resign as a Member of Parliament for Clacton-on-Sea, thereby forcing a by-election".

"I've decided that the people of Clacton should be the judges of my actions," he says.

He adds: "And that is why I will be putting my name forward to stand in this by-election. I will fight to win. I will fight to continue the political revolution that Reform has started."

He calls it a "people versus the establishment" by-election.

Farage says he is resigning as MP for Clacton, triggering a by-election in the constituency - which he'll stand in.

We'll bring you more on this shortly.