Glasgow Councillor Aileen McKenzie claims she was falsely accused of sleeping with Mr Sarwar by a fellow member after writing the blog.
Cllr McKenzie has also claimed her declaration of support for Mr Sarwar saw her removed from an online group run by the Campaign for Socialism, which wants to see Richard Leonard installed as Scottish Labour leader.
“Even though I’m from the left of the party I was keen to write something in support for Anas, because I had worked with him for many years and I admire him as a politician,” Cllr McKenzie said.
“I did expect some backlash on social media, but nothing on the scale that I experienced. Someone even suggested that I must be sleeping with him and that was why I was supporting him.”
Cllr McKenzie claimed the allegation was posted by a Labour member, who was an acquaintance.
“The person did delete the tweet, but I can’t understand why he did it. Anas is married and I have a partner and a child, so the allegation was obviously untrue. Some of the other online abuse was incredible. This is my eighth leadership campaign since I joined the Labour Party, but this has definitely been the worst.”
An online message from the Campaign for Socialism sent to Cllr McKenzie said: “The executive currently has a couple of memberships under review, including yours, for either standing against SLYS (Scottish Labour Young Socialists)/CfS (Campaign for Socialism) candidates in the SEC (Scottish Executive Committee) contest – or for providing active political support for candidates standing against those who we have actively agreed to support.”
Last night a source close to the Campaign for Socialism said it was a sensible precaution for her membership of the online group to be temporarily reviewed, because the forum was used to discuss aspects of Mr Leonard’s campaign.
A spokesman for the Anas Sarwar campaign said: “It’s disappointing that this lengthy election has not always been conducted in the comradely spirit that most of us hoped for. We must leave the divisions of the past behind us.”
A spokeswoman for Mr Leonard’s campaign said: “Our campaign has stuck to policy and politics from day one and we have been clear, just as the Labour Party is, that there is no place for any type of abuse in this campaign.”