John Swinney could become Scotland’s first minister as early as next week after the woman who would have been his main rival for the job announced she will not be running.

Hours after Mr Swinney confirmed he is standing to succeed Humza Yousaf as SNP leader and first minister, former Holyrood finance secretary Kate Forbes issued a statement saying she will not run against him.

Nominations for the position do not close until Monday, but Ms Forbes’s decision could pave the way for Mr Swinney to replace Mr Yousaf unopposed.

It comes after a week of drama at Holyrood, sparked by Mr Yousaf announcing last Thursday that he had terminated the powersharing agreement the SNP had with the Scottish Greens.

Kate Forbes backed John Swinney for the SNP leadership as she ruled out a run for the top job herself (Jane Barlow/PA)

That decision ultimately brought to an end his 13-month tenure as First Minister.

He announced his resignation on Monday, saying he would stay on only until a successor is found.

While Ms Forbes had run against Mr Yousaf for the leadership last year, she has now given her backing to former deputy first minister Mr Swinney.

She said: “I have concluded that the best way to deliver the urgent change Scotland needs is to join with John Swinney and advocate for that reform agenda within the Scottish Government.

“I can therefore today announce that I will not be seeking nomination as the next SNP leader.

“John will therefore have my support and endorsement in any campaign to follow.”

She acknowledged her decision might leave some “disappointed”, but insisted Mr Swinney understands the “need for reform” and is “committed to delivering it”.

Along with the support of Ms Forbes, Mr Swinney has also won the backing of key SNP figures including Westminster leader Stephen Flynn, Health Secretary Neil Gray and Education Secretary Jenny Gilruth, meaning it seems almost certain he will become the new SNP leader without a contest being held.

After 16 years in the Scottish Government, serving in positions including as finance secretary and education secretary, there had been suggestions he would take on the role on an interim basis.

But at his campaign launch on Thursday morning, he insisted he will seek to lead the SNP through this year’s Westminster election and the next Holyrood poll in 2026.

He made clear: “I am no caretaker. I am no interim leader.

“I am offering to lead my party through the Westminster elections and to lead us beyond the 2026 elections – two contests which I intend to win for the SNP and for Scotland.

“My message is crisp and simple – I am stepping forward to bring the SNP together, deliver economic growth and social justice, to deliver the very best future for everyone in a modern, dynamic, diverse Scotland.”

Humza Yousaf announced on Monday he is stepping down as First Minister and SNP leader (Andrew Milligan/PA)

He also told supporters: “I want to unite the SNP and unite Scotland for independence,” as he conceded the party is “not as cohesive as it needs to be”.

Mr Swinney served as party leader between 2000 and 2004, but stepped down in the wake of the SNP’s performance in the European election that year.

He said on Thursday: “Having served as a senior minister for 16 years, having helped steer Scotland so close to independence in 2014, I want to give all I have in me to ensure the success of our cause.

“I believe I have the experience, the skills and I command the trust and the confidence of people across this country.”

John Swinney praised Kate Forbes as he officially launched his bid to be the next SNP leader and Scottish first minister (Jane Barlow/PA)

While the Scottish Greens had said they could no longer work with Mr Yousaf after he terminated their powersharing agreement, it is thought the smaller pro-independence party would be able to work with Mr Swinney.

However the Greens are unlikely to have been able to work with Ms Forbes because of her more socially conservative views.

Mr Swinney praised the former finance secretary – who he had private talks with earlier this week – describing her as an “intelligent, creative, thoughtful person who has much to contribute” to public life.

Promising she would play a “significant part” in his team, he added: “If elected I will make sure Kate is able to make that contribution.”

However, Scottish Conservative leader Douglas Ross said Ms Forbes had “caved into SNP demands for a stitch-up to install John Swinney as leader and spare the party the bloodbath of another leadership contest”.

The Tory hit out at “this shady backroom deal” as he branded Mr Swinney a “failed former leader”.

Mr Ross insisted: “Scotland deserves better than someone whose fingerprints are all over 17 years of SNP failure and secrecy.”

Scottish Labour leader Anas Sarwar said: “The people of Scotland are crying out for change – but all the SNP is offering them is yesterday’s man in John Swinney.

“John Swinney was the finance minister who broke the public finances, the worst education secretary in the history of the Scottish Parliament, the deputy first minister who deleted evidence meant for the Covid inquiry and the man who has been at the heart of this incompetent SNP Government for the past 17 years. ”

Meanwhile, Scottish Liberal Democrat leader Alex Cole-Hamilton said Mr Swinney had “more baggage than an airport carousel”

“For more than two decades, John Swinney has been complicit in every moment of the SNP’s division, neglect and failure,” he said.