MSP Amanda Bland has quit Reform UK Scotland to sit as an independent.
The resignation relegates the party to the third-largest group at Holyrood, with one member fewer than Labour.
A Reform UK source told Scotland News that Bland was “very difficult to work with” and had been called to a meeting on Wednesday to discuss a high turnover of staff in her office.
Bland, who represents Central Scotland and Lothians West, said her “principles and priorities remain unchanged” but gave no details of why she had left the party.
In a statement she said: “I entered politics to champion fairness and common sense, protect women and children, improve public services, support businesses to thrive, and work towards a fairer and more effective criminal justice system.
“As a member of the criminal justice committee, I remain committed to scrutinising legislation, holding the justice system to account and supporting practical measures that improve public safety, protect victims and ensure justice is served.
“Holding the Scottish government to account remains a key priority, and I believe I can best pursue these goals as an Independent MSP.”
She said she would not be making any further statements or giving interviews about Reform, and that her focus now was on her responsibilities as an independent MSP.