Justice secretary David Gauke has announced he is backing Rory Stewart as Conservative leader.
The cabinet minister said the leadership hopeful was "not motivated by wishful thinking" and would "bring the country together".
"He is an excellent communicator, someone that can bring the country together and he is someone who is setting out the true choices and options that exist on Brexit," he told talkRADIO's Julia Hartley-Brewer.
"He is not motivated by wishful thinking. He is telling the truth and setting out the real choices, and I think he would make an excellent Prime Minister."
Mr Gauke said his second place contender would be Matt Hancock who was "running a really good campaign", and in at third, Michael Gove.
"Rory is the person I want to win," he added.
"I worked with Rory in the Ministry of Justice for 16 months. I have seen what an impressive minister he is, both good at strategy, the big picture stuff, but also completely on top of the details."
Mr Stewart caused division among his supporters last week after it emerged he had once smoked opium during a trip to Iran.
He said smoking the class-A drug at a wedding more than a decade ago was a "stupid mistake".
But his admission also won him support online, with some social media users praising his honesty.
One Facebook user wrote: "Well he just went up in my estimation. He should never have apologised though."
And Twitter user @hotflushblondie added: "You don't need to apologise we have all done things we regret but it's part of growing up."