Kate Forbes has quit the Scottish government after new first minister Humza Yousaf tried to demote her.
The former finance secretary, who was narrowly defeated by Yousaf in the race to succeed Nicola Sturgeon, was offered the rural affairs brief in his new cabinet.
A source close to Forbes said she “told him where to stick it” and resigned instead.
The move is a major setback for Yousaf as he tries to unite the SNP after being elected party leader yesterday.
It came just hours after he was confirmed as Scotland’s first minister following a vote by MSPs.
Yousaf defeated Forbes by 52% to 48% following a bitter five-week leadership contest, during which she criticised his record as a minister.
However, he had signalled he intended to heal the divisions by taking a “Team SNP” approach to forming his new government.
He said: “Where there are divisions to heal, we must do so quickly.”
Forbes will now return to the backbenches.
A senior SNP figure told HuffPost UK: “It’s a very poor start by Humza. He’s essentially ignoring the wishes of nearly half the party members.”
In her first comment since quitting government, Forbes paid tribute to Yousaf.
She tweeted: “He has been respectful, supportive & warm throughout. In whatever capacity I serve, I’ll support him. Ps after 5 long weeks, I’ll be delighted to see more of my family!”