Jeremy Corbyn in election pitch against 'corrupt system'

Jeremy Corbyn will pledge to take on “the few who run a corrupt system” as he kicks off the Labour Party’s general election campaign.

The Labour leader will promise to “rebuild” public services and hit out at “tax dodgers, dodgy landlords, bad bosses and big polluters”.

In a speech on Thursday, Mr Corbyn will say the poll is a “once-in-a-generation chance to transform our country”.

But Prime Minister Boris Johnson blamed Mr Corbyn for the delay to Brexit.

Mr Johnson said the UK’s failure to leave the EU by 31 October had been caused by Mr Corbyn “insisting upon more dither”.

Ahead of a series of campaign visits of his own on Thursday – the day Brexit had been scheduled to take place – Mr Johnson said: “I didn’t want an election. Like the country, I wanted to get Brexit done – but [an election] is the only way forward.”

Mr Johnson suffered a blow on Wednesday evening as cabinet minister Nicky Morgan became the latest Tory MP to decide not to stand for re-election. Ms Morgan said the abuse MPs faced was one reason for stepping down.

Five weeks of official election campaigning are expected to get under way once Parliament is formally shut down next Wednesday.

In a speech in London, Mr Corbyn is expected to say Labour will launch “the biggest people-powered campaign in history”.

“You know what really scares the elite? What they’re actually afraid of is paying their taxes. So in this election they’ll fight harder and dirtier than ever before,” he will add.

“They’ll throw everything at us because they know we’re not afraid to take them on.”

But the Conservatives’ campaign chairman James Cleverly said voting for Labour was “precisely the opposite” to a “vote for change”.

He said Labour would offer “more delay and uncertainty on Brexit, meaning the government can’t focus on people’s priorities, like the NHS, schools and crime.”

Jeremy Corbyn will draw a stark contrast between Labour and the Conservatives – accusing his rivals of protecting the privileged few and promising real change if Labour wins office.

His scathing attack on the elite and what he calls a corrupt system is a clear if unsurprising sign he intends to run a radical campaign – one which he believes can deliver him the keys to No 10.

The Tory campaign looks likely to be dominated by a promise to deliver Brexit, before moving on to domestic priorities such as schools, hospitals and crime.

Culture Secretary Nicky Morgan said she would not contest her Loughborough seat again – adding that being an MP had had a “clear impact” on her family.

“The abuse for doing the job of a modern MP can only be justified if, ultimately, Parliament does what it is supposed to do – represent those who serve in all areas of public life, respect votes cast by the electorate and make decisions in the overall national interest,” she wrote.

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More than 50 incumbents are preparing to stand down – and there may be more announcements in the coming days.

Ms Morgan’s former colleague Anna Soubry – who left the Conservative Party and is now leader of Change UK – told BBC Newsnight that both Mr Johnson and his predecessor, Theresa May, were guilty of a “remarkable” and “pitiful lack of response” to the abuse MPs had faced in recent years.

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Meanwhile Liberal Democrat leader Jo Swinson has defended her decision to campaign as a “candidate to be prime minister”, denying such an outcome was a fantasy.

Ms Swinson told the BBC’s Andrew Neil the UK was in a “very volatile political situation” and anything could happen on 12 December.

“We have seen many unprecedented political results in recent years,” she said.

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As other smaller parties geared up for their election campaigns, the Daily Telegraph reported that the Brexit Party was considering helping the Tories to secure a majority by withdrawing hundreds of its general election candidates.

Brexit Party sources told PA news agency the report was “wild speculation”.

What happens next?

• Having been approved by the Lords, the early election bill will receive Royal Assent – when the Queen formally agrees to the bill becoming law
• On Monday 4 November, MPs are due to elect a new speaker to replace John Bercow
• Just after midnight on Wednesday, 6 November, Parliament will be shut down or “dissolved” – meaning every seat in the House of Commons becomes vacant
• The electoral authorities have set a deadline of the end of Tuesday 26 November for people to register to vote.
• The cut-off point to apply for postal votes is the same day, but at 17:00 GMT.