Boris Johnson has backed Andrea Leadsom for the Tory party leadership.
In a clear bid to exact revenge against his former campaign manager Michael Gove, the former London Mayor said the Energy Minister was the only candidate who could unite the party after the Brexit vote.
Johnson, whose own leadership ambitions imploded in spectacular fashion last week after Gove's decision to stand, said that Leadsom was the best person to offer the "zap" and drive for the country.
The first round of voting for the Tory leadership takes place on Tuesday, when Leadsom, Gove, Stephen Crabb and Liam Fox will all try to keep up with frontrunner Theresa May in the contest.
All the candidates attended lenthy hustings meetings on Monday evening and one of them will drop out of the race on Tuesday as the list is whittled down to four or even fewer contenders.
"Andrea Leadsom offers the zap, the drive, and the determination essential for the next leader of this country," Johnson said in a statement.
"She has long championed the needs of the most vulnerable in our society. She has a better understanding of finance than almost anyone else in Parliament. She has considerable experience of government.
"She is level-headed, kind, trustworthy, approachable and the possessor of a good sense of humour.
"She has specialised in the EU question and successfully campaigned for leave and will be therefore well-placed to help forge a great post-Brexit future for Britain and Europe.
"Above all she possesses the qualities needed to bring together leavers and remainers in the weeks and months ahead. I will be voting for Andrea Leadsom tomorrow."
Leadsom launched her campaign on Monday morning, and has attracted many of the Right of the Tory party.
She was forced to distance herself from UKIP after Nigel Farage backer Arron Banks used his Leave.eu campaign to back her candidacy.
Leadsom also stumbled at the hustings meeting arranged by the backbench 1922 Committee, when trying to explain her policy to help improve babies' "frontal lobes".
One MP described her performance as "a car crash", while another said she "lost the room" the moment she mentioned her 'attachment theory' for young children.
Others said that May struggled to answer questions on the economy, while no one mentioned Gove's 'treachery' in any questions to him. "But it was the elephant in the room," one MP said afterwards.