MSP James Dornan has become the first politician to declare his intention to run in the SNP depute leadership election.

He made his announcement yesterday saying he wanted to “build on the strong links” with grassroots activists as “we move forward to independence”. Meanwhile, Brexit minister Mike Russell ruled himself out of the contest to succeed Angus Robertson, who stood down on Saturday.

Paying tribute to Robertson, Russell told The National: “I can confirm completely and categorically that I will not be a candidate. Angus would be a very hard act to follow and the role is a very demanding one which rules me out at the start as I am completely focused on Brexit.

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Alongside the demands of my huge, diverse constituency of Argyll and Bute, that takes up all my time. I have no intention of being distracted from those responsibilities.

“In any case, I have been an active senior member of the party for more than 30 years, having been first elected to national office in the SNP in 1987.

“I can’t go on forever and there are many other people – including younger people – who would do an excellent job. I look forward to supporting one of them.”

Russell is among the SNP politicians best known to the public due to his position in highlighting the possible economic and constitutional implications of Brexit for Scotland. He is a former education secretary and was a candidate in the 2004 leadership election, won by Alex Salmond.

Dornan, who holds the position of convener of the Education Committee at Holyrood, made his announcement on social media as speculation mounted about who would enter the race.

His intervention follows comments made by senior figures to The National that strategies to achieve independence would be the key focus of the contest, expected to formally begin next month.

Announcing his intention to stand in a social media post, Dornan said he would be seeking nominations for the position.

The Glasgow Cathcart MSP, tweeted: “As of February 5th 2018, I would like to announce that I will be seeking nominations for the position of depute leader for the Scottish National Party, when the process commences.”

Speaking to The National, he said: “I have decided to seek nominations for the position of depute leader of the Scottish National Party as I think it’s important we continue the momentum built during the great job Angus Robertson did.

“With a new depute comes new challenges and opportunities and I’m confident that now is the right time for me to use my strengths and connections to build on the already strong links between grassroots activists, party members and the SNP leadership as we move forward to independence.

“I am strongly of the opinion that the focus of the party should always be here in Scotland and that is another reason why I, as an MSP, am putting my name forward today.”

It is expected that the next depute will come from the Westminster group, although Finance Secretary Derek Mackay and Transport Minister Humza Yousaf have been mentioned as possible contenders.

It is understood that Tommy Sheppard, the Edinburgh East MP, and a candidate in the 2016 depute leadership contest, is considering a bid, as is Edinburgh South West MP Joanna Cherry.

It is probable that one or the other will stand, as both are seen as left-wingers and possibly regarded as more in tune with the grassroots membership than Westminster group leader Ian Blackford, a former investment banker. Blackford has said he is not ready to make an announcement.

Among other potential candidates is Kirsty Blackman, deputy leader of the Westminster group, who yesterday posted a link on social media to an article she had written for The National on independence.

Some within the SNP believe a passage in Robertson’s resignation letter, in which he emphasised his mandate as deputy as a “Westminster SNP leader and parliamentarian representing a rural constituency”, was meant as an endorsement for Blackford.

But former minister Alex Neil said he believed there should be a contest and it made sense for the depute to be Westminster-based as the leader is at Holyrood. The winner is likely to be unveiled in June.