Labour leader Jeremy Corbyn will lash out at the 'hypocrisy and dishonesty' of Theresa May's Tories when he addresses Saturday's Durham Miners' Gala.
The Labour leader will use his Big Meeting speech to claim he is leading a "government-in-waiting" which could end austerity and scrap the cap on public sector pay rises but only if the
party can stay united.
Mr Corbyn will tell the event the Grenfell Tower tragedy underlines the "terrible consequences" of cutting public spending.
He will say: "It is the hypocrisy that turns the stomach, when in the terrorist attacks or the Grenfell Tower fire, these Conservative politicians give warm words of praise and then a week
later vote to cut those same people's incomes, having cut thousands of their colleagues' jobs already.
"People are fed up with the hypocrisy and the dishonesty of the Conservative Party.
"There's always the money available when they want to start another war.
"There's always the money for tax giveaways to big business or the very richest.
"There's always the money for new grammar schools or the latest hare-brained scheme to benefit their friends."
He will add: "We saw at Grenfell Tower the terrible consequences austerity and of doing things on the cheap."
Vowing to tackle inequality, he will say: "We will turn this monstrosity around and build a fairer, more equal Britain."
Labour's better than expected general election performance has secured Mr Corbyn's position but there is concern among some Labour MPs about moves which could make it easier to
oust them in favour of candidates from the party's left.
Since the election, Mr Corbyn has also been hit with a rebellion over Brexit which saw 49 of his MPs defy him by calling for the UK to stay in the single market and customs union.
The Labour leader will warn that indiscipline could jeopardise the party's chance of success.
"We are no longer just in opposition but a government-in-waiting," he will say.
"We have a huge opportunity now to change our country for the better if we learn the lessons of this great movement, stay united, stay disciplined and work together."
Mr Corbyn has spoken at the gala several times before, both as a backbench MP and Labour leader.
The event brings large crowds to the centre of Durham to watch the banners and brass bands parading through the city.
An estimated 200,000 people could gather in the historic centre to take in the spectacle and enjoy the huge funfair.
And many thousands gather on the Old Racecourse to hear the political speeches in the afternoon.
There will be additional security for this year's event with more road closures than in previous years and more armed police on visible patrol.