Nigel Farage vowed defiance today despite massive pressure to stand more Brexit Party candidates down in Labour marginals.
The MEP dismissed pleas from his own allies such as Arron Banks to avoid splitting the Eurosceptic vote, saying they were suffering from 'Brexhaustion'.
Instead he condemned Boris Johnson for refusing to give way in Leave-voting Labour heartlands where the Conservatives could 'never' win.
He said if the PM had been willing to do that, a third of Labour voters in some crucial target seats would have followed his advice to endorse the Tories.
Making clear hundreds of Brexit Party candidates will be nominated by the deadline of 4pm this afternoon, Mr Farage said: 'The job of the Brexit Party is to hold him to account, because too many times over the last three years the Conservatives have made promises and not delivered.'
Mr Farage has said he will field candidates in every Labour-held seat - in a move that could hamper Tory efforts to win a majority.
Nigel Farage has condemned Boris Johnson (pictured on a train from Paddington this morning) for refusing to give way in Leave-voting Labour heartlands where the Conservatives could 'never' win
Mr Farage (pictured with boxer Derek Chisora in Essex yesterday) is still refusing to back down any further in the election struggle with the Tories
The PM stopped short of urging Mr Farage to withdraw his candidates from Tory-Labour marginal seats last night.
But there are claims the Tories offered an informal pact that would have meant it only fielding 'paper' candidates against 40 Brexit Party hopefuls.
But asked about the report in the Daily Telegraph, a Tory source said: 'We don't do electoral pacts as we have been very clear on.'
A Brexit Party source said: 'At every election the Tories have upwards of 100 paper candidates.
'If this offer was made it was an offer of the status quo, in in other words, no offer at all.
'It looks like an attempt to portray the Brexit Party and Nigel Farage as unreasonable, despite the huge concessions that we have made, both on a policy and on the unilateral decision not to stand in the 317 Tory held seats.'
Speaking on Radio 4's Today Programme, Mr Farage said: 'The job of the Brexit Party is to hold him (Boris Johnson) to account, because too many times over the last three years the Conservatives have made promises and not delivered.'
Mr Farage (pictured at a rally in Essex yesterday) has said he will field candidates in every Labour-held seat - in a move that could hamper Tory efforts to win a majority
He added: 'This all started way back in September when I sent to Number 10 some polling that said that in their 40 key seats, if I endorsed their Conservative candidate, one-third of Labour voters in those seats would vote Conservative on a one-off basis to get a genuine Brexit done.
'And ever since that time, what I've realised is that the