Economy Secretary Keith Brown has joined the contest to become the SNP's new depute leader.
Mr Brown is the third candidate and the most senior figure to come forward.
He said getting the party ready to fight and win elections and any future referendums would be his focus in the role.
The depute leadership position became available when Angus Robertson stepped down in February.
Mr Brown told The National newspaper that he had been approached by a number of party members and elected members asking him to stand.
"I've taken the advice of senior colleagues past and present, people I like and respect, and I'm pleased to be putting my name forward," he told the newspaper.
"There's a serious job for the depute leader in supporting Nicola and getting the party in shape to face the future."
He added: "The SNP is also the biggest party in Scotland by a long way and we need to get all of our members ready to fight and win elections, and to be ready for any future referendums - getting the party ready and giving the members the tools they need will be my focus."
Mr Brown served with the Royal Marines before entering politics and was first elected as an MSP in 2007.
He has held a number of ministerial roles since 2009.
Glasgow MSP James Dornan and Julie Hepburn, who has worked for a number of senior figures in the SNP, have already declared as candidates.
Westminster leader Ian Blackford and several high-profile MPs including Pete Wishart, Johanna Cherry and Tommy Sheppard have ruled out putting their names forward.