Nicola Sturgeon is facing a legal threat to release key documents in the Alex Salmond inquiry or be taken to court.
Scottish Conservatives gave the government an ultimatum in the long-running attempt to put evidence before a Holyrood probe.
A committee of MSPs is examining how in 2018 the SNP Government botched the investigation of sexual misconduct allegations by two female officials against Salmond.
The former First Minister pursued a judicial review and it was agreed the 2018 internal probe had been unlawful.
The flawed Government probe cost the taxpayer over £500,000 and ended the long-standing friendship between Salmond and Sturgeon.
MSPs looking into the shambles have been complaining for months about the lack of clarity or access to what they consider key evidence.
Today, Scottish Tory leader Douglas Ross said a vote demanding publication at parliament has already been “ignored”. A second attempt is being made in Holyrood on Wednesday.
Ross said: “I have instructed the party to start preparations for launching legal action if the government refuses to listen to the Scottish Parliament and release these key documents.
“They have already ignored one vote in the Scottish Parliament. If they ignore a second vote this week, the Scottish Conservatives as the lead opposition party will seek to deliver what MSPs across the Scottish Parliament have demanded.
“The committee is being obstructed and blocked from doing its job. The First Minister’s promises to co-operate fully have been broken.
“If the government continues to abuse its power to shut down scrutiny, the Scottish Conservatives will look to force their hand so we can find out how more than £500,000 of taxpayers’ money was lost.”
The row centres on legal advice received by the government for Alex Samond’s own legal challenge at judicial review.
A former SNP minister, Alex Neil, and the convener of the Alex Salmond inquiry committee have also called for more transparency from the government.
The inquiry is separate to the criminal trial in which Salmond was cleared of all charges. He’s always denied any wrongdoing.
Last week, committee convener Linda Fabiani slammed the latest "unacceptable" delay to the probe after the Scottish Government refused to send two senior civil servants to a hearing.
Deputy First Minister John Swinney wrote to the inquiry to claim that having witnesses at its next session on Tuesday "would create an unacceptable risk" in relation to jigsaw identification of the complainers in the court case.
