A second former Tory MSP has left the party to join the Scottish People's Alliance.
Lyndsay McIntosh was the Tories' social justice spokeswoman
Lyndsay McIntosh, the Conservatives' former social justice spokeswoman, followed the lead of Keith Harding.
They will both stand for the centre-right SPA in the Scottish Parliament elections on 1 May.
Ms McIntosh said it had become clear when the Tories selected their list candidates for the Central Scotland region that she could not be elected.
She said: "It was clear five months ago that I could not be elected as a Tory. Since then I have seen out my term of office and, in the words of one senior Tory, I have served with 'distinction' until the very last day."
She denied that the switch had been motivated solely by an attempt to get elected.
"If I did not think that the Scottish People's Alliance had a lot to offer people of Scotland I would not do this," she said.
"I find there are a lot of policies there, a lot of things that people will find attractive, people who simply would not have been attracted to politics under any other circumstance."
SPA campaign director Bruce Skivington said:
"We are sure she will be a great asset to the Scottish People's Alliance and believe that in joining, she adds further credibility to our party and our policies."
Mrs McIntosh is to stand as both a first past the post candidate and as a prospective list MSP for central Scotland.
It is no coincidence that they have chosen to jump ship after the rankings process was complete
Mr Harding, who was the Conservatives' local government spokesman at Holyrood, will contest the Stirling seat for the SPA.
A Tory spokesman said it was "ludicrous" to suggest that there were any substantial policy differences between the pair and the rest of the party.
"Neither of them has dissented on any major issue over the last four years," he said.
"It is no coincidence that they have chosen to jump ship after the rankings process was complete, and it was clear they had lost the confidence of the party members.
"The truth is they have far more chance of being elected, no matter what their ranking, in the Scottish Conservative Party than they have with their new party."