Throughout the weekend a number of candidates announced they would not be standing for the role of leader.
Keith Brown, who is depute leader of the SNP, said he would not be standing.
He was followed by Neil Gray, minister for international development, and environment minister Màiri McAllan, who both made announcements on Twitter.
Scottish Health Secretary Humza Yousaf and former minister Ash Regan have announced they will stand to succeed Nicola Sturgeon as SNP leader, with Kate Forbes expected to make an announcement today.
Ivan McKee told BBC Radio Scotland’s Good Morning Scotland programme: “Kate has some big decisions to make, of course this happened while she was on maternity leave, she was not planning to come back until the beginning of April and as we all know the announcements of last week were a surprise to everyone.
“So Kate has had to assess her position, understand what can be done but my understanding is that she has considered that and will be making an announcement later today and we shall see what she’s got to say.”
Mr McKee said he would be backing Ms Forbes if she decides to run.
He said: “I think Kate is a hugely talented individual, I’ve had the pleasure of working with her over the past seven years and seen first hand what she is able to deliver, her focus on the things that are important to Scotland and her ability to engage with people on a very real and authentic level and persuade them of her case.
“And I think those talents, to be able to deliver excellent public services, a strong economy, a green economy for Scotland and to be able to persuade people of the case for the SNP and for independence, are exactly the assets we need in a leader.”
Deputy First Minister John Swinney, the SNP's Westminster leader Stephen Flynn and high-profile MP Joanna Cherry have already said they will not run to lead the party.
Potential candidates yet to announce include Ms Forbes and Scottish Constitution Secretary Angus Robertson – with both the favourites at the bookmakers to be the next SNP leader and First Minister.
Ms Forbes has long been seen as a potential successor to the First Minister.
She was thrust into the limelight by having to step in and deliver the Scottish budget at the 11th hour in 2020 after her predecessor Derek Mackay resigned in disgrace.
But the MSP for Skye, Lochaber and Badenoch, who is a Free Church of Scotland member, could be at odds with the wider party – and current policy – on some social issues, including the hotly-debated gender reforms blocked by the UK Government.
Candidates have until Friday to secure 100 nominations from at least 20 local branches to secure their place on the ballot, with the new SNP leader being announced on March 27.