Former environment secretary Owen Paterson, who is backing Mrs Leadsom, said it was “quite remarkable” the former City trader had “come from absolutely nowhere” to win a “strong” second place in the ballot.
He added: “I’m really confident she’s in tune with the membership. She sees Brexit as a huge opportunity for this country.”
Tory MPs had voted throughout the day in a secret ballot that ended at 4pm.
Of the 330 Tory MPs, 329 voted in today’s ballot meaning Mr Cameron is likely to have again been the only Conservative MP not to have cast a vote.
The election had last night been hit by claims Mr Gove’s team were organising a ‘stop Leadsom’ campaign to prevent the energy minister winning through to the final pairing.
It has been suggested Mrs Leadsom, a key Brexit backer, could prove more popular with the Tory grassroots than Remain-supporting Mrs May, in contrast with the Home Secretary’s greater support among MPs.
Earlier today, Mrs Leadsom had said she believes Britain can be the “greatest nation on Earth” outside of the EU in a leadership rally.
On Tuesday, ex-defence secretary Liam Fox and Work and Pensions Secretary Stephen Crabb both dropped out of the race after the first ballot of MPs.