Ian Murray confirms deputy bid with attack on 'architects of failure'
The 43-year-old retained his Edinburgh South seat with a majority of more than 11,000 in the December election.
In the early hours of the morning after the vote, Mr Murray was critical of Jeremy Corbyn and used his own victory speech to criticise the leadership for helping to deliver "the worst Conservative prime minister in history".
He said: "The architects of the party's catastrophic failure in 2019 cannot be allowed to be the architects of the response.
"The next leadership team must turn us into an election-winning machine that uses the skills and talents of all our members and supporters to succeed.
"To win again we will need to beat the odds, and I know how to win by building broad coalitions of support.
"The Labour Party must change. We must be honest with ourselves so we can be honest with the voters.
He adds: "We must become a credible alternative government of the future, not a protest movement of the past.”
The former shadow Scottish secretary becomes the sixth candidate to declare in the contest.
The Shadow sports minister Rosena Allin-Khan also confirmed her candidacy on Tuesday morning. Ms Allin-Khan, a medical doctor of Polish-Pakistani origin, said Labour must abandon the “ideological purity” that was rejected by voters in last month’s general election.
Shadow education secretary Angela Rayner, shadow justice secretary Richard Burgon, shadow equalities secretary Dawn Butler and shadow Europe minister Khalid Mahmood are also standing for deputy leader.
On Monday, the party's ruling National Executive Committee agreed the timetable for the leadership and deputy leadership elections, with the results to be announced at a special conference on April 4.
When asked who he was backing in the leadership contest, Mr Murray told the BBC's Good Morning Scotland radio programme: "I don't think it's right for the deputy leadership candidates to be backing a particular leader because the deputy will have to work with anyone that's put in place.
"What we do need is someone who can bring fresh ideas and a fresh approach because a new face and a new voice but the same direction is someone the party should be rejecting.”
Six candidates have announced they intend to stand for the leadership: Shadow business secretary Rebecca Long-Bailey, shadow Brexit secretary Sir Keir Starmer, frontbenchers Emily Thornberry and Clive Lewis, and backbenchers Jess Phillips and Lisa Nandy.