Nigel Farage today complained that Britain 'broken' and in 'cultural decline' as he launched Reform's 'contract' with voters today.
The former MEP denied the state of the country was a failure of Brexit, insisting it was down to the implementation.
He said he had not expected to come out of 'retirement' to fight the election, but argued there was a 'huge gap' between the desires of the public and what the main parties were offering.
'We are not pretending we're going to win this election,' he conceded. 'That is not possible in this election.'
Earlier, Mr Farage said he was 'absolutely' aiming to be in Downing Street by 2029 despite conceding that his party could get six million votes and only a few MPs.
The boast came as Reform's crucial day got off to a shaky start - with deputy leader David Bull wrongly claiming that the Office for Budget Responsibility watchdog has signed off its spending plans.
The document includes commitments to slash £50billion off public spending, leave the European Court of Human Rights, and ban all 'non-essential' immigration.
The party is also proposing making St George's Day and St David's Day bank holidays, and abolishing the BBC licence fee.
The insurgents are billing its proposals a 'contract' as Mr Farage says the public has lost faith in the term 'manifesto'.
The document is being unveiled in Merthyr Tydfil, Wales, as Reform tries to show that it is taking on Labour as well as the Tories.
Mr Farage said the location was chosen 'because it shows everyone exactly what happens to a country when Labour is in charge'. He said Wales had drifted in a 'leftist, woke direction'.
Underlining his pitch to voters, Mr Farage said: 'You might not want to vote for what we say. But we do say what we mean.'
Nigel Farage insisted he wants to be PM by 2029 today as he launched Reform's manifesto
Mr Farage arriving to launch the 'contract' in Merthyr Tydfil this afternoon
Reform deputy leader David Bull wrongly claimed that the Office for Budget Responsibility watchdog has signed off its spending plans
A Survation poll has suggested Reform could get seven seats - but Mr Farage has admitted that first past the post means they could get six million votes and no MPs
Mr Farage said: 'We are not pretending that we are going to win this General Election, we are a very, very new political party.'
He added: 'This is not something with which we're going to govern the country. That's not possible in this election.
'Although this election is for our party, and for me, the first important step on the road to 2029.
'Our ambition is to establish a bridgehead in Parliament, and to become a real opposition to a Labour government.'
He said the Tories would not be able to provide opposition because 'they spend most of their days arguing among themselves, and they're split down the middle when it comes to policy'.
Mr Farage said there needs to be a 'rethink' on the NHS, saying: 'We're not getting bang for our buck and there's a growing level of disenchantment that the health service simply isn't fit for purpose not just in the way that it used to be, the way that we want it to be.
'So let's look at other funding models, let's look at how the French do it, let's be radical in our thinking.'
Interviewed on Sky News this morning, Dr Bull was asked if Reform had shown its plans to the OBR and respected IFS think-tank.
'We have and we've spoken to top economists…' he replied.
Pressed by Kay Burley on what the OBR had said about the manifesto, Dr Bull said: 'I can't tell you what the OBR said because I didn't speak to them… '
Challenged on how he knew they had been consulted, Dr Bull said: 'Because I do, because we know that we've had due diligence across all our policies.'
When Burley probed whether he was sure about the OBR being asked, Dr Bull said: 'As far as I'm aware, yes.'
The presenter reminded him that he said the watchdog was 'definitely' consulted.
'OK, I'll go with definitely. We will have done,' he replied.
An OBR spokesman said: 'The OBR is prohibited from considering policies that are not announced by the Government and has not evaluated any party manifestos.'
Speaking to BBC Radio 4's Today programme, Mr Farage said: '(The Conservatives) can't agree on anything, they're split down the middle, and we know what we stand for, we know what we believe in, and for democracy to function properly there needs to be a proper voice of opposition.
'And our plan – and this is our first big election as a party – our plan is to establish that bridgehead in Parliament and to use that voice to build a big national campaigning movement around the country over the course of the next five years for genuine change.'
Asked if he would seek to be PM at the next election - due by 2029 - Mr Farage replied: 'Yes, absolutely. I think the disconnect between the Labour and Conservative Westminster-based parties and the country – the thoughts, hopes and aspirations of ordinary people – are so far apart from where our politics is.'
Mr Farage claimed the idea that Donald Trump wanted to overturn a democratic election is a 'matter of opinion', adding: 'What happened on January the 6th should not have happened, of that there's no doubt whatsoever. Did he actually urge people to storm the Capitol building? No, he didn't.'
When pressed on the issue, he said: 'No, I don't approve of objecting to elections, even though I object to much of what's happening in our system, with postal vote corruption and many other things.'
Senior Conservative figure David Davis warned that Farage was 'trying to destroy' the Tories, as the party continued to see Reform eating into their vote.
He told Times Radio: 'Farage is trying to destroy the Conservative Party. That is his explicit aim.
'When somebody tries to burn down the golf club, you don't offer them membership, do you?'
Ex-Cabinet minister Robert Jenrick took his attack to Richard Tice, accusing the Reform chairman of being a Labour 'sleeper agent'.
Mr Jenrick added: 'I not only understand the frustrations of Reform voters, I share them.
'But a vote for Reform can only deliver a Labour one-party state that increases taxes and immigration.'