Wendy Alexander has announced her decision to step down as leader of the Scottish Labour party following controversy over donations.
The MSP for Paisley North had come under increasing pressure after a standards committee ruled this week that she should be suspended from the Scottish parliament for one day after failing to declare donations to her leadership campaign.
Ms Alexander has previously claimed she acted in good faith and in accordance with initial written parliamentary guidance.
Announcing her decision to step down today, she said: "It is with deep regret that I have tendered my resignation follow the decision of the parliamentary committee.
"I hope the events of recent days will lead to reflection by all MSPs and parliamentary officials of the appropriateness, objectivity and effectiveness of current procedures.
"Some may feel they have achieved a political victory but wiser heads will ask 'at what price?'"
Scottish general secretary Colin Smyth said deputy Labour leader Cathy Jamieson would become acting leader of the Labour group of the Scottish parliament until a new leader is elected.
Ms Jamieson said her former leader's decision to quit "put the Scottish parliament and the Labour party above her own interests".
"Ever since this process began anybody who knows Wendy Alexander has not for one minute questioned her integrity as is evident today," she added.
"There are far wider issues that have been raised and it is not just about Wendy Alexander and the Labour party but parliamentary process.
"Wendy Alexander followed the code of conduct, sought advice from parliament and received unambiguous legal advice.
"Subsequently the standards commissioner decided this advice was wrong and the Standards Committee then penalised her for following the advice of the parliamentary authorities. This has profound implications for all MSPs."