Jeremy Corbyn will today ratchet up the election campaign rhetoric, accusing Boris Johnson of trying to “hijack Brexit to sell out our NHS” to Donald Trump.

In a keynote speech, the Labour leader will promise to “get Brexit sorted” in six months and warn the Prime Minister will reverse hard-won workers’ rights to unleash nothing less than “Thatcherism on steroids” by running down their entitlements to holidays, breaks and leave.

Despite Mr Johnson’s repeated insistence that the NHS is not for sale in a post-Brexit trade deal with America - last week the US President himself rejected such a notion - Mr Corbyn has placed the allegation at the centre of his bid for power and will claim the Conservative leader is preparing to “betray our NHS in a sell-out to Trump”.

HeraldScotland: Camley's Cartoon: NHS takes centre stageCamley's Cartoon: NHS takes centre stage

Last night, the PM hit back, writing a letter to the Labour leader, saying his Brexit policy would return Britain to “square one” and that his promise of a second referendum would “destroy all faith in our democratic process”.

He asked Mr Corbyn to confirm that if he had to rely on SNP and Liberal Democrat votes in Parliament to run the country, he would “never be willing to revoke Article 50?” ie scrap Brexit.

Mr Johnson, who will chair a special election Cabinet today ahead of the Tories’ expected campaign launch later this week, insisted: “We cannot afford to spend 2020 fighting two more referendums offering the public more of the same confusion and indecision that have plagued the last three years.”

This morning in a campaign event in the target seat of Harlow in Essex, the Leader of the Opposition will focus his attack on what he believes is the Conservative betrayal of the NHS.

He will say: “Johnson stood in front of a bus and promised £350 million a week for the NHS. Now we find out £500m a week could be taken out of the NHS and handed to big drugs companies under his plans for a sell-out trade deal with Donald Trump.

“We now know US and UK officials have been discussing drug pricing in secret and the US Government is demanding ‘full market access for US products’. Senior NHS managers have said that would mean ‘higher prices for medicines,’ which will ‘pass on costs to both patients and the NHS’.

“Behind the scenes, the Conservatives have tried to suppress the news, attacking the BBC for reporting what we and health professionals are saying. This is what they don’t want you to hear: a vote for Johnson’s Conservatives is a vote to betray our NHS in a sell-out to Trump.”

Claiming a Tory trade deal with the US President would put a “price-tag on our NHS,” Mr Corbyn will stress: “We’ll say it again and again until the message gets through to the White House: our NHS is not for sale.”

In graphic language, the Labour leader will warn how a Conservative Government would want a “race to the bottom” in standards and protections.

It would slash food standards to US levels, where “'acceptable levels' of rat hairs in paprika and maggots in orange juice are allowed and they’ll put chlorinated chicken on our supermarket shelves”.

And Mr Corbyn will argue a re-elected Johnson Government would want to move Britain towards a more deregulated American economic model.

“In the US, workers get just 10 days’ holiday a year, big business gets free rein to call the shots and tens of millions are denied healthcare. What Boris Johnson’s Conservatives want is to hijack Brexit to unleash Thatcherism on steroids,” he will declare.

Yesterday, speaking on the campaign trail outside Monklands Hospital in Airdrie, Richard Leonard issued a similar warning, saying: “Trump's position is America First and there's no doubt that any agreement, if ever that was to be reached with the US in a bilateral trade deal, would see the opening up of parts of our public realm in this country to private interests based in America."

The Scottish Labour leader added: "People are rightly concerned about what that would do to access to drugs companies. People are rightly concerned about what that would do to the provision of services in our NHS.”

Ahead of their General Election launch in London today, the Liberal Democrats said if they gained power, they would stop Brexit in its tracks and use a £50 billion “Remain Bonus” to invest in public services and tackle inequality.

The Lib Dems calculate this is the amount of money the UK economy would grow by if the country stayed in the EU, benefitting from higher public sector receipts.

Jo Swinson, the party leader, said: “Brexit has taken far longer and cost far more than anyone said it would. But any form of Brexit will damage our jobs, our economy and our public services, starving them of vital cash as the economy struggles along.”

She added: “Every vote for the Liberal Democrats is a vote to stop Brexit, build a brighter future and invest the £50bn Remain bonus in our vital public services.”

In other developments:

*Brexit Party leader Nigel Farage vowed to target the five million Labour voters who backed Leave in the referendum as he unveiled his party's 600 election candidates;

*Downing St made clear there would be no extension to the planned transition period, ending in December 2020;

*the Lib Dems, the Greens and Plaid Cymru were said to be moving towards a pro-Remain election pact, which could involve each of them standing down candidates to give the best chance to the anti-Brexit campaign in certain seats;

*peers urged the Government to think again about publishing a controversial report into alleged Russian interference in the UK democratic process ahead of the election as No 10 made clear the necessary clearance process had not yet been completed and

*Jean-Claude Juncker, the former European Commission President, said in an interview with Der Spiegel magazine that during the EU referendum “so many lies were told; including by current Prime Minister Boris Johnson”.