Personal tensions between the pair go back at least as far as their time on opposite sides of the Brexit referendum campaign. Senior figures in the Scottish Conservatives have struggled in vain to block Johnson’s route to 10 Downing Street, dubbing their plot “Operation Arse”.
Last week saw the leader of the Scottish party give her strongest public criticism of the former foreign secretary since the start of the leadership race, suggesting Johnson’s victory would undermine the Union.
“I want to see him make assurances that it’s not Brexit do or die, it’s the Union do or die,” she said, in response to Johnson’s commitment to leave the EU on 31 October, with or without a deal.
But despite the majority of Scottish Tory MSPs following Davidson in backing the challenger, Jeremy Hunt, sources in Johnson’s campaign said he was committed to winning over detractors in Scotland.
“Boris is a huge admirer of Ruth – he’s fascinated by her,” a close supporter of Johnson’s campaign said. “He’s totally in awe of her ability to win people over and convince them that she thinks and feels the same way they do about an issue, just from walking into a room and meeting them. They’re alike in that way.”
An ally of Davidson’s among the Scottish Tories at Westminster dismissed the comments, saying: “She’ll hate that.”
Davidson endorsed Sajid Javid for the Tory leadership and then rushed to back Michael Gove ahead of the ballot of MPs to choose the final two candidates.
Reports suggest she contrasted Gove’s honesty in addressing revelations about past cocaine use with Johnson’s reluctance to face questions from the media and his denials over potentially damaging stories about his own past conduct.
During the 2016 EU referendum campaign, Davidson accused the Leave campaign led by Johnson of having “lied”. But with the former foreign secretary a strong favourite to beat Hunt, Davidson and Scottish Secretary David Mundell have both said they would work with Johnson if he becomes prime minister.
Polling has confirmed the findings of internal Scottish Conservative Party surveys that Johnson is as unpopular in Scotland as Jeremy Corbyn.
Johnson last week insisted he has a “very good relationship” with Davidson. And the Johnson campaign source said he would continue to ask his Scottish supporters for guidance on his approach north of the border as Prime Minister.
The two contenders will face off in front of Scottish members at a hustings event on Friday..