Richard Leonard said a bid to oust him at a meeting of the party's ruling body is 'entirely factional'.
Senior Labour MP Rachel Reeves pointed to 'pretty dire' poll ratings for Scottish Labour.
The Highlands politician, who has served as a councillor, MP and MSP, will step down aged 65.
Leader Richard Leonard said the Labour Party was a ‘broad church’ and should remain so.
Speaking at First Minister's Questions, Richard Leonard said his uncle had died in a care home with the virus.
Ian Murray was recently appointed as Labour's shadow Scotland secretary.
The Dumbarton MSP defeated Glasgow councillor Matt Kerr by 10,311 votes to 7528 to win the role.
The legislation tabled by Scottish Labour MSP Monica Lennon is aimed at ending period poverty.
Scotland's only Labour MP has launched a bid to become the deputy leader.
Labour councillor Alison Evison will speak at the Local Government Association conference.
All the Scottish party leaders are out on the campaign trail ahead of Thursday's election.
Figures published by ISD Scotland show the number has increased by 55 on last year.
Neale Hanvey had been due to contest the Kirkcaldy and Cowdenbeath constituency.