Scottish Liberal Democrat leader Willie Rennie said he would bring forward a private members’ bill to introduce a power to recall MSPs, matching a similar procedure introduced at Westminster in 2015.
Voters would get the chance to force an MSP to face a snap by-election if there is support from between ten and 20% constituents.
Mr Rennie said he would raise the proposal with other party leaders at Holyrood this week. It follows anger at the lack of sanctions for Mr McDonald, the Aberdeen Donside MSP, who resigned as children’s minister last year and quit the SNP last week after an internal inquiry found he sent “inappropriate and unwanted text messages” and “exploited his position of power” over female staff.
However, there is no means to force Mr McDonald to stand down from his £62,000 a year job as an MSP. Claims that he subjected a member of staff working for SNP MSP James Dornan to “harassment and sexual innuendo” could lead to his suspension by the Holyrood Standards, Procedures and Public Appointments Committee.
Mr Rennie told the Mail on Sunday: “Action is required as it is unacceptable for Mark McDonald to continue as an MSP. I am hopeful MSPs of all parties would back this plan.”
In 2013, when the former nationalist MSP Bill Walker initially refused to stand down despite a conviction for domestic abuse, Mr McDonald joined calls from parliamentarians for him to go.
The proposal has already gained broad cross-party support. A Scottish Labour Party spokesman said: “Mark McDonald’s behaviour has clearly been unacceptable and he should stand down.
“We support the principle of recall and will work with other parties to see how it could work in practice. Scottish Labour leader Richard Leonard would be happy to meet Willie Rennie to discuss his plans.”
A Scottish Tory spokesman said: “If the last few weeks have taught us anything, it’s that a system needs to be created to ensure this doesn’t happen again. But if a system of recall is pursued, we have to be extremely careful about the circumstances under which this can activated.”
The Scottish Greens said they would wait for the outcome of a probe by the Commissioner for Ethical Standards in Public Life in Scotland before deciding whether to support a Recall Bill.
A Scottish Government spokesman said Mr Rennie’s proposal would be for parliament to decide.