Michael Gove has insisted Boris Johnson is "speaking from the heart" on Brexit during a debate on talkRADIO with Julia Hartley-Brewer.
Gove was speaking as part of a panel with former Tory co-chairman David Davis and Katie Perrior, Theresa May's former spin doctor, during a debate moderated by Julia Hartley-Brewer.
The panel also discussed Jeremy Corbyn, with Perrior suggested his supporters behaved like drug-addled megalomaniacs at the recent Labour Party Conference.
When asked about Johnson's recent article on Brexit which has caused such friction within the Tory Party, Gove said "he's speaking from the heart.
"One of the things about Boris is he threw himself into the campaign to get us out of the European Union. All sorts of criticism was directed him for taking a leading role in that campaign, and there were people who questioned his motivation.
"I was campaigning alongside him and I know that his motivation was to make sure that our country could take back control and its something about which he feels deeply and passionately.
"No-one could have written that article, no-one could have expressed themselves that way unless it came from the heart.
"Any attempt to find any other motivation, other than just a commitment to making an optimistic case for Britain outside the European Union, I think they're barking under the wrong tree."
Shapps, the MP for Welwyn Hatfield, concurred with Gove's view, saying "he absolutely believes in Brexit. Of that I have no doubt at all."
Although many have criticised Johnson for writin two separate draft articles - one backing Leave, the other Remain - ahead of the Brexit referendum, Shapps insisted "that is a perfectly reasonable thing for him to have done, to weigh up the arguments in his mind. It's perfectly possible to feel strongly about an issue and feel both sides."
"My belief is that he always wanted this country to leave."
Perrior, who quit as May's communications chief after the Prime Minister announced a snap election earlier this year, said she wouldn't have allowed Johnson to write the now-infamous Brexit article, but said the Foreign Secretary is "a bit damned if you do, damned if you don't", because if he stays in the background, people will ask where he is and why he is not being more vocal.
'They treat him like the Messiah'
On the subject of Corbyn Perrior was far more strident, telling the debate "Not everyone is being represented by Jeremy Corbyn right now. We shouldn't fall for the hype."
Having been in Brighton during Labour's recent conference, Perrior said Corbyn's suppoters treating him with "Messiah-like" genuflection, adding "I was blown away by all the optimism.
"It was like they were taking copious amounts of speed and they decided to act like they were going to run the world."
Corbyn, she said, advocated "spending money like chocolate buttons" and the Tories must match his extravagant promises with "political will" rather than try to produce lavish spending pledges of their own.
Shapps agreed with Perrior's criticism of the Corbynistas, saying "everyone in this room has run the gauntlet to get into Conservative Party Conference. Why? because there are Socialist Workers outside, there are extremists carrying banners that are pretty offensive."
He said colleagues had been greeted with taunts of "Tory scum", adding "there is no Conservative equivalent of that when Labour go to their conference. People of the centre-right don't behave like that to our opponents on the centre-left. They have a different way of expressing themselves."
To counter this sort of passionate political campaigning, Shapps says theTories must reinforce their activist network by training grass-roots campaign managers.
"We had 100,000 people knocking on doors in 2015," Shapps said. "We were Momentum before Momentum.
"But we allowed that to be disbanded. We didn't replace it with anything else. A snap election was called and we were screwed."