SNP Westminster leader Angus Robertson has confirmed he will run for the party's deputy leadership.
Mr Robertson, 46, said he would stand in the race to replace Stewart Hosie, who quit after newspaper disclosures about an affair.
First elected in 2001, the high-profile Moray MP was behind the SNP's successful campaign at last year's general election.
He wrote on Twitter: "Big job to protect Scotland's place in Europe, which is why I am running for the deputy leadership of @theSNP."
Mr Robertson told the Sunday Herald newspaper: "The SNP has a huge responsibility to protect Scotland in Europe. Since the EU referendum result, many colleagues from Holyrood, Westminster and the SNP grass roots have asked me to run for the deputy leadership.
"It would be an honour to work with Nicola Sturgeon as her deputy and bring together our parliamentarians, councillors and record number of party members for the next big challenge.
"With much work to do to protect our place in Europe we have to promote Scotland, focus on the economy and investment, and the key powers to deliver fairness and success in Scotland.
"After nearly a decade's experience as Westminster SNP leader and as campaign director who has helped deliver national SNP election victories, I think I have the range of experience to fulfil this important role."
Inverclyde SNP councillor Christopher McEleny is so far the only other declared candidate, although MEP Alyn Smith and MP for Edinburgh East Tommy Sheppard are reported to be considering whether to run for the post.