Theresa May is "battling for Britain" against European Union (EU) countries who want the UK to fail, a Cabinet minister has claimed.
Health Secretary Jeremy Hunt said a bad Brexit outcome could be a "disaster" for the NHS as he repeated Tory claims that Brussels officials were attempting to undermine the Prime Minister.
His comments came as a British former ambassador to the EU criticised Mrs May's approach to the crucial Brexit talks.
Lord Kerr, who wrote Article 50 - the European legal process for Brexit, said the Government had spent "more time negotiating with itself" than seeking the views of the 27 other EU states.
Mr Hunt's comments, on BBC One's Andrew Marr Show, come after the Prime Minister's explosive claim that European politicians and officials were seeking to meddle in the outcome of the June 8 General Election.
The Health Secretary said: "If we don't get a good Brexit outcome and we don't protect the economic recovery, the jobs that so many people depend on whose taxes pay for the NHS; if we get a bad Brexit outcome, that would be disaster for the NHS.
"The choice that people face is do they want a strong Theresa May doing those very difficult negotiations - we've got 27 countries lined up against us, some of them appear to think that for the EU to survive Britain must fail."
He added: "There is something very different about this election because, in a normal election, you are choosing a prime minister for the next five years, but this time we are choosing a prime minister who will do the Brexit negotiations that will last for generations."
Mr Hunt said it was "very plain for everyone to see" how Brussels was seeking to influence the election, pointing to the leaks about a difficult dinner in Downing Street attended by European Commission president Jean-Claude Juncker.
"They didn't have to leak these reports to newspapers of dinners that happened in the middle of an election campaign," he said. "It is the wrong approach to negotiations."
He added: "The answer is very clear that they are trying to leak reports that undermine Theresa May's position."
The impact of Brexit on the NHS is highly contentious, with fears about the citizenship status of EU medics and the lingering row about the Leave campaign's pledge of extra funding once contributions to Brussels have ceased.
Mr Hunt said: "We think getting a good deal would be better for the NHS, better for all of us.
"We also recognise that a bad deal would be bad for the country, bad for our long-term future and we are not prepared to say we will get a deal at any cost."
Lord Kerr told BBC Radio 4's Broadcasting House that the UK should be "on the front foot" in the negotiations but Mrs May had failed to properly set out her position.
"Why haven't we put forward a proposal for the framework for the future relationship which has to be agreed under Article 50? The words are in Article 50.
"You can't settle the money without settling on the future framework. Why haven't we put forward a draft framework describing how on, say, foreign policy, security policy, anti-terrorism, anti-global warming, anti-crime?
"We want to remain very close to these people, who are our most important partners and neighbours. I feel that we missed a tactical point there but I think it's also a strategic point.
"There is a degree of doubt in Brussels about whether we really mean what we say about special partnership."
He added: "I think it has not surprisingly taken the Government quite a long time to make up its mind what it's asking for.
"I think it's spent more time negotiating with itself and negotiating inside the Conservative Party than it has in scoping out the landscape in 27 member states."
Liberal Democrat health spokesman Norman Lamb said: "Jeremy Hunt has confirmed that a bad Brexit deal will be a disaster for the NHS - the Liberal Democrats have been saying this all along. The NHS is already in crisis and Theresa May's push for a hard Brexit will only make things worse.
"This is just another example of why the people must be given a say on the final Brexit deal."
Shadow foreign secretary Emily Thornberry dismissed the allegations made about Brussels interference as "just nonsense" and hit out at Mrs May.
"This wasn't the behaviour of somebody who wanted to negotiate, I think that she was either paranoid and delusional or she was simply being manipulative," she told BBC Radio 4's The World This Weekend.
"She is saying things that cannot be unsaid. If you behave in a way whereby you are giving every impression you want to flounce off into the mid-Atlantic and you don't want to negotiate, we will not be getting a good deal."
Home Secretary Amber Rudd said the "aggressive" tactics from Brussels should not have been deployed during the General Election campaign.
She told BBC Radio 5 Live's Pienaar's Politics: "It seems very clear that they did meddle insofar as they put out these very unhelpful, slightly hostile, comments both in terms of the potential leak - I don't know how much of it was true in terms of the gossip that came from the dinner - and then putting out that Theresa May shouldn't be leading the negotiations, and then somehow supporting this idea that there was a 100 billion euro (£84 billion) bill.
"This is quite aggressive negotiating tactics."