Following his speech to the party’s conference on Monday, Douglas Ross told journalists that a timeline for a vote of no confidence in Nicola Sturgeon will be announced.
Mr Ross said the First Minister lied to parliament over when she knew about allegations of harassment against Alex Salmond which if proven would be a breach of the ministerial code, and he would look to oust her in the final weeks of the parliamentary session.
The First Minister referred herself for investigation to the independent adviser on the ministerial code, James Hamilton, who is currently looking into the allegations.
In his conference speech, Mr Ross said: “The evidence against Nicola Sturgeon is overwhelming and mounting up every day.
“If we allow her to get away with this, then we say that the truth is worthless in Scottish politics.
“We can’t let more than £500,000 wasted, lies to Parliament and the mother of all cover-ups, go without challenge.”
Mr Ross went on to implore other parties in Holyrood to back the vote, saying: “So, we will bring that vote of no confidence in the First Minister.
“Win or lose – we will put all the damage that she has done out there for all to see.
“We will not hold back. From now to May, we’re not going to back off an inch.
“I would urge the other parties to get behind us, to stand up for truth, stand up for our parliament, stand up to the SNP.
“We have the votes, don’t cave in again, don’t duck this chance to be counted,
“Don’t let Nicola Sturgeon get away with this.”
But less than a minute later, Mr Ross attacked the Greens as “lackeys” of the Scottish Government, the Lib Dems as “teetering on the edge of political extinction” and said the Labour Party were “weak, full stop”.
When asked if this was a wise strategy to win support from other opposition parties, Mr Ross said: “They can see the evidence that’s very clear to the Scottish Conservatives and people across Scotland.
“It’s undeniable that Nicola Sturgeon has lied to the Scottish Parliament and the Scottish people, she and her government have wasted hundreds of thousands of taxpayers’ money with a case that they were told by their lawyers would not be successful.”
Mr Ross added: “If political leaders are so sensitive about what other political leaders say about them, then they shouldn’t really be in politics if that’s a determinant on how they vote.”
The Tories previously failed in their bid to oust Deputy First Minister John Swinney after he did not release legal advice following two votes by MSPs in Holyrood.
Once the motion was lodged, Mr Swinney agreed to release “key legal advice”, which was enough to secure the support of the Scottish Greens and keep him in post.
A spokesman for Nicola Sturgeon said: “The fact that the Tories announced this vote before the First Minister had even appeared before the parliamentary committee to give evidence shows that this was always about grubby politics rather than supporting the women who were badly let down.
“One by one, the conspiracy theories and smears thrown at the First Minister in this whole affair have been demolished by the documentary evidence – and yet Douglas Ross and the Tories still choose to indulge them.
“The First Minister and the SNP Government are entirely focussed on leading Scotland through the pandemic, which is exactly what the people of Scotland would expect – and it is becoming ever clearer that on the issues that matter, the Tories under Douglas Ross have absolutely nothing positive to offer.”