“I can confirm that I will be putting my name forward to be prime minister of this country,” the environment secretary said, speaking outside his London home.
“I believe that I'm ready to unite the Conservative and Unionist Party, ready to deliver Brexit, and ready to lead this great country.”
Mr Gove – who will set out his detailed pitch later today – is expected to argue he has a proven record running government departments, which makes him more “capable” of delivering Brexit.
His decision to run is the biggest threat to Mr Johnson, the overwhelming favourite, and will electrify a contest that threatened to become a procession.
It will revive memories of the extraordinary twist in 2016, when Mr Gove was Mr Johnson's campaign chairman – only to declare he was unfit to be leader and launch his own doomed candidature.
Since then, Mr Gove has rebuilt his reputation as an energetic, pro-green environment secretary and impressive Commons performer on Brexit, in stark contrast to Theresa May.
He is expected to argue he has a better “track record” than Mr Johnson, who was a controversial foreign secretary, and argue he is a “unity” candidate.
Mr Gove will also argue that, while his rival was the main face of the Vote Leave campaign, he was entrusted with some of the key TV debates which would also feature in a general election.
However, he will struggle to beat Mr Johnson if he reaches the final choice – to be made by the Europhobic Tory membership – having stayed loyal to the prime minister’s Brexit deal, which they loathed.
Furthermore, Tory MPs who appear ready to swing behind Mr Johnson in order to “save their seats” at an election, will be aware that Mr Gove has terrible poll ratings with the public.
The other six names in the crowded field are: Jeremy Hunt, the foreign secretary, Rory Stewart, the international development secretary, Matt Hancock, the health secretary, Andrea Leadsom, the former Commons leader, Dominic Raab, the former Brexit secretary, and Esther McVey, the former work and pensions secretary.
The last three, all Brexiteers, have already matched Mr Johnson’s pledge to crash the UK out of the EU on 31 October if necessary, if the EU refuses to renegotiate.
Mr Gove will be under pressure to follow suit – while both Mr Hancock and Mr Stewart have spoken out against a no-deal Brexit.
Meanwhile, Philip Hammond warned that MPs will topple any new Tory prime minister trying to force through a crash-out Brexit and sensationally threatened to join the revolt himself.
The chancellor refused – three times – to rule out joining the no-confidence vote that Labour has vowed to table if a hardline Brexiteer wins the race.
Mr Hammond said any new leader trying to “push through a no-deal exit on 31 October” would immediately face the prospect of having to “leave office”.
“It would be very difficult for the prime minister who adopted no-deal as a policy to retain the confidence of the House of Commons,” he said – just minutes after Dominic Raab made that exact threat.
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