The Scottish health secretary Humza Yousaf and former minister Ash Regan have announced their bids to stand to succeed Nicola Sturgeon as leader of the SNP.
The pair made their announcements in the Sunday Mail newspaper, with Mr Yousaf describing the time since Ms Sturgeon announced her resignation as a "rollercoaster of emotions".
They are the first candidates to officially declare their intention to stand.
It comes as SNP depute leader Keith Brown said that he will not be in the running - despite calls for him to do so from "parliamentary colleagues and senior office bearers".
Mr Yousaf said: "You've got to put yourself forward if you think you're the best person for the job. And I do. This is the top job in the country, and it needs somebody who has experience."
The Glasgow Pollok MSP has been viewed as a potential successor to Ms Sturgeon since he first entered Holyrood in 2011.
He has been a perennial frontbencher in every SNP administration since, but has become mired with controversy in recent years surrounding the Hate Crime and Public Order (Scotland) Bill - which faced criticisms over its impact on freedom of expression - and his stewardship of the NHS, which faced the hardest winter in its history in recent months.
Announcing her bid, Ms Regan said she believes she is the right person to "bring back unity, draw a line under certain things and move past them".
She referred to getting the NHS "back on its feet" following the COVID pandemic, boosting the economy, creating jobs and dealing with the cost of living crisis.
The former community safety minister has been referred to as a rebel SNP MSP after she resigned in protest against the Gender Recognition Reform (Scotland) Bill, and has since become an outspoken critic of the legislation.
She has also called for SNP members who left in the past year to be given a vote in the leadership race - a move described as "preposterous" by deputy first minister John Swinney.
In a post on Twitter on Sunday, Ms Regan also outlined a plan to call for an independence convention to be held to "create a new vision of an independent Scotland".
She said a pro-independence majority at any election in Scotland should be enough to trigger negotiations to leave the UK.
Should this happen under her leadership Ms Regan said: "We will invite the Westminster Government to the Scottish Government to commence negotiations and a timeframe for Scotland's withdrawal from the UK."
Depute leader rules himself out of race
Other potential candidates yet to announce their bids include finance secretary Kate Forbes and culture secretary Angus Robertson.
Mr Swinney ruled himself out to be next the leader, as did Stephen Flynn, the SNP's Westminster leader.
Environment minister Mairi McAllan was reported to be weighing up a run but announced on Sunday she would not stand, saying "now is not the right time".
Scottish justice secretary and depute leader Mr Brown, who is well liked within the party, also put to rest rumours of a candidacy.
"I have come to the conclusion that, as depute leader, I can best serve the interests of the SNP by supporting the party through the forthcoming process and providing a degree of continuity as we come to terms with Nicola's resignation," he said.
"I believe that we can and must move on to the exciting opportunities ahead in building further support for an independent Scotland.
"In doing so, we must never forget our responsibilities to the people of Scotland as their elected government."
Mr Brown said he would not endorse a candidate for the leadership, but other senior party figures have publicly backed the two candidates who declared in the past 24 hours.
Ukraine minister Neil Gray ruled himself out of running and threw his weight behind Mr Yousaf, who also won support from former minister Graeme Dey and MPs Anne McLaughlin and Joe FitzPatrick.
Meanwhile Ms Regan secured the support of MP Joanna Cherry, who has also been critical of the current SNP leadership.
SNP MP Angus MacNeil told Sky News that the party has a number of options to choose from following Ms Sturgeon's surprise resignation.
"There are other capable people such as Jenny Gilruth or Ivan McKee, or I think Kate Forbes is going to put her hat into the ring as well," he said.
"But one of the things that we do have is a depth of talent in the SNP."
Candidates have until Friday 24 February to receive more than the threshold of 100 nominations from at least 20 local branches.
If more than one candidate passes that mark, an election will be triggered, culminating on 27 March.