The Scottish Government has been accused of trying to force through a gender reform law before Christmas to prevent the threat of the SNP Finance Secretary quitting.
Forbes, who is rumoured to be sceptical of the bill, is on maternity leave and expected to resume her Cabinet duties next year.
Tory MSP Alexander Burnett claimed Ministers were opposed to kicking scrutiny of the Bill into next year in order to avoid a resignation.
The Gender Recognition Reform Bill aims to speed up the time it takes for a trans person to obtain a gender recognition certificate (GRC) and lowers the age for obtaining one from 18 to 16.
Ministers also want to drop the requirement for a medical diagnosis of gender dysphoria and the need for a doctor’s report.
Opponents such as author J.K Rowling believe the plans could threaten women’s sex-based rights and be exploited by violent men.
The draft bill was backed at its first stage by MSPs in October, despite an unprecedented rebellion by nine SNP MSPs.
This included Ash Regan, who quit Nicola Sturgeon’s Government over concerns she had about the planned law.
A final vote is scheduled days before Christmas, but the Tories want more time to debate the proposals.
Speaking at Holyrood, Burnett said: "We are simply asking that adequate time be given to this Bill for scrutiny, and that this does not come at the expense of other important business.
“So what possible reason could the Scottish Government have for being so opposed to having stage 3 in the new year?
“Whispers and rumblings from around the parliament, including in some SNP corridors, conclude that it is to do with... making sure that the Scottish Government doesn't lose any more ministers. That is, quite simply, not an acceptable reason to rush legislation.”
Forbes, who gave birth in August, was one of 15 SNP politicians who signed a letter in 2019 which called on the Government not to “rush” into legislation.
George Adam, the Scottish Government Parliamentary Business Minister, said: “The reality... is that an extra week was given between stage 2 and stage 3 because that was asked by one of the business managers.”
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