A Commons committee has said official copies of Acts of Parliament should be printed on archive paper to save money.
But member David Amess, Southend West MP, told the BBC he had had "second thoughts" and vellum should remain.
Fellow member James Gray, MP for North Wiltshire, said switching to paper would save "very little money, if any".
He was late for the meeting in October when the Commons Administration Committee decided to back a call from Lord Laming that Acts of Parliament should be recorded on "high-quality archive paper" instead of the vellum.
It said specialised printing on vellum cost too much and top quality archive paper could last for 500 years.
Lord Laming said the "slightly over Â£100,000 per year" cost of vellum could not be justified, when archival paper was "superior for print quality". An online database of legislation is also kept.
The change must be agreed in the House of Commons, which rejected a previous bid to ditch vellum in 1999.
Now one committee member has changed his mind.
"I should have given more careful consideration to what we had been asked to decide upon. I now believe that I made a mistake in not voicing my concerns then," Mr Amess told BBC Sunday Politics West.
"It's very precious and is at the heart of the United Kingdom's tradition as being the mother of all parliaments."
Paul Wright, manager of vellum manufacturer William Cowley, said he was "gobsmacked" at the committee's decision. He calculated the average yearly cost at nearer Â£47,000.
North Wiltshire MP Mr Gray said vellum would last for 5,000 years at least and "can be kept in an ordinary cupboard" while paper would require "a new archive centre" with environmental controls to stop it degrading.
"I can't think why it is that this committee in Parliament are thinking about changing something that's done perfectly well for 1,000 years. It's a real piece of Parliamentary history," he said.
An MP who backed moves to scrap Parliament's centuries-old tradition of printing laws on calf skin has admitted he "made a mistake".