Ruth Davidson has backed Sajid Javid to be the next Tory leader, saying he has a vision to unite a "divided Britain".
The Scottish Conservative leader said Mr Javid's life experience and knowledge made him the best candidate for the job and to be the next PM.
Writing in the Scottish Mail on Sunday, she said he embodied the party's values of "aspiration, education, opportunity, hard work and just reward".
The home secretary is one of 11 MPs hoping to replace Theresa May.
Mrs May officially stepped down as the leader of the Conservative Party on Friday, but will remain as prime minister until her successor is chosen.
Ms Davidson said Mr Javid had the professional attributes to "chart the best course" for the UK on Brexit.
She also backed him "in the secure knowledge he will defend Scotland's interests and is an instinctive and committed Unionist".
Responding to her endorsement Mr Javid said: "So proud to have Ruth's backing. There's nobody like her. Together, we're going to show what modern Tories can do."
'Born into poverty'
Announcing her support for Mr Javid in a 1,000-word article, Ms Davidson said: "Born into poverty, he worked his way to a better life for himself and his family before walking away from a lucrative career in order to give back in public service to the country he loves."
She added: "With Britain now so deeply divided, we need our next prime minister to be a unifier."
Former banker Javid, the son of immigrant parents from Pakistan, "isn't just best placed to tell the story of modern Britain, he embodies it", she said.
Who will replace Theresa May?
The winner of the contest to lead the Conservative Party will become the next prime minister.
Announcing his candidacy for Conservative Party leader, Mr Javid pledged to deliver Brexit and has said he believes it is possible to negotiate a new deal with the EU.
But he has also said he would be prepared to leave the EU without a deal if that proves impossible.
Ms Davidson added: "Saj is uniquely placed as the only candidate with vast experience of international business, coupled with an intimate knowledge of security arrangements, to chart the best course for us."
Highlighting Mr Javid's proposals for a £100bn fund to invest in UK infrastructure if he becomes prime minister, Ms Davidson said he "knows that the nation does well only if no part of it is left behind".
The leadership nominations will close at 17:00 BST on Monday.
Candidates need eight MPs to back them. MPs will then vote for their preferred candidates in a series of secret ballots held on 13, 18, 19 and 20 June.
The final two will be put to a vote of members of the wider Conservative Party from 22 June, with the winner expected to be announced about four weeks later.
On Tuesday 18 June BBC One will be hosting a live election debate between the Conservative MPs who are still in the race.
If you would like to ask the candidates a question live on air, use the form below. It should be open to all of them, not a specific politician.
If you are reading this page on the BBC News app, you will need to visit the mobile version of the BBC website to submit your question on this topic.