Nigel Farage has said he will not be standing as a candidate in the general election on 12 December.
The Brexit Party leader told the BBC’s Andrew Marr he had thought “very hard” but had decided he could “serve the cause better” by supporting his party’s 600 candidates “across the UK”.
“I don’t want to be in politics for the rest of my life,” he said.
Mr Farage, who has stood unsuccessfully for Parliament seven times, also criticised the PM’s nBrexit deal.
The 55 year-old told BBC One’s Andrew Marr Show the deal agreed earlier this month was “virtually worse that being in the EU”.
“If Boris Johnson was going for a genuine Brexit, we wouldn’t need to fight against him in this election,” he said.
On Friday, the prime minister rejected an alliance with Mr Farage’s Brexit Party, telling BBC political editor Laura Kuenssberg doing deals with “any other party… simply risks putting Jeremy Corbyn into Number 10”.
Mr Farage had called on the prime minister to drop his Brexit deal, unite in a “Leave alliance” or face a Brexit Party candidate in every seat in the election.
He told the Marr show: “I always thought that to win an election, get a big majority so we can get a proper Brexit, a coming-together would be the objective.
“I still hope and pray it happens but it doesn’t look like it will.”
Mr Johnson maintains that the only way out of the EU is to “go with the deal we’ve got”.
The prime minister told Sophy Ridge on Sky that he was “deeply, deeply disappointed” to miss the 31 October deadline to secure Brexit, calling it “a matter of deep regret”.
The PM had previously said he would rather “die in a ditch” than ask the EU to delay Brexit beyond Halloween.
Mr Johnson told the programme that he was sorry, and took responsibility, for missing the date, but accused Parliament of failing to implement his deal.
He also said Donald Trump was “patently in error” when the US president warned the government’s Brexit deal would hamper a UK-US trade deal.
Mr Farage said Mr Johnson’s deal “kills off any chance of genuine independence”.
“If Boris is determined to stick to this new EU treaty, then that is not Brexit,” he said.
Analysis by political correspondent Jessica Parker
Some people, political opponents of Nigel Farage, will accuse him of running scared – suggesting he is not going to run because he thinks he is not going to win.
Perhaps the flip side of this is that Mr Farage – rather than concentrating on one constituency where he personally might win – has made it clear he is going to try to make life for Boris Johnson pretty difficult if this Leave alliance doesn’t happen.
And it doesn’t look like it will.
Treasury minister Rishi Sunak hit back at the criticism of the deal, telling the same programme: “I campaigned for Leave, I spent a lot of time talking to my constituents and others across the North East and in Yorkshire – what do they want from Brexit?
“They want to end free movement and replace it with a points system, they want to end the fact that money keeps going to the EU year after year, they want to make sure we’re in control of our laws, and also they want us to have an independent trade policy. These are all things the prime minister’s deal delivers.
“What I would say to Nigel Farage is, sometimes in politics, as in life, you’ve got to take yes for an answer.”