Scottish Labour has suspended MSP Alex Rowley from the party at Holyrood amid claims about his conduct.
The Fife MSP stepped aside from his roles as interim and deputy leader after allegations he had sent abusive text messages to a former partner.
In a statement, Mr Rowley rejected the allegations and said he would work to clear his name.
The party subsequently announced it would be removing the whip from him for the duration of the investigation.
Mr Rowley referred himself to the party's investigation unit and announced he would step aside from the leadership after claims were published in The Scottish Sun.
He had been absent from the Scottish Parliament for the past two weeks, with party bosses citing a chest infection. Fellow MSP Jackie Baillie, who had been filling in for him at first minister's questions, has now been appointed interim leader.
After former leader Kezia Dugdale said she would have suspended Mr Rowley had she still been in charge, both leadership candidates - Anas Sarwar and Richard Leonard - said he should be suspended.
Party business manager James Kelly subsequently announced that the MSP would have the whip withdrawn in the Scottish Parliament throughout the probe.
In a statement Mr Rowley said: "I totally refute these allegations and will take all steps necessary to clear my name.
"These allegations must be properly and thoroughly investigated in line with our party's procedures - and I will refer myself to the party so such an investigation can take place.
"While that investigation is carried out, I will step aside as deputy leader, as well as interim leader, of the Scottish Labour party."
Mr Rowley, who previously served as election agent for former prime minister Gordon Brown, has been standing in as the Scottish Labour leader since Ms Dugdale stood down in August.
In a statement, Ms Dugdale said that had she remained in charge, she would have suspended Mr Rowley from the party while the "serious and deeply concerning" allegations were investigated.
This was subsequently echoed by both candidates to replace her as leader. Mr Leonard said suspension would be "appropriate", while Mr Sarwar said there were "clear procedures" which meant he should be suspended "while a robust, fair and thorough investigation is carried out".
The party then announced he would be suspended from the Labour whip in the Scottish Parliament.
Mr Kelly said: "It is important that the investigation into these allegations is fair and transparent, and the matter will be thoroughly investigated using the Labour Party's internal complaints procedure.
"However, in light of the serious nature of the allegations, Labour at Holyrood has taken the decision to remove the whip from Alex Rowley for the period of this investigation."
The winner of the party's leadership contest is due to be announced this weekend.
Mr Rowley's position as interim leader had previously been questioned when he was caught on tape backing Mr Leonard as the "best candidate".