A bid to increase the number of donated organs available for transplant looks set to fail after Labour MPs were ordered to vote against it.
Currently only people who have consented can have organs removed
A bill introduced by Lib Dem Evan Harris aimed to replace the current donor card with a system that would have presumed patients' consent.
Both Lib Dem and Conservative MPs have a free vote on the issue, unlike on the government benches.
Labour's Stephen Pound said his party chiefs' decision was "ridiculous".
The normally loyal backbencher predicted a "fair few" backbenchers would defy the whips in a vote on Monday.
He told BBC Radio 4's Today programme: "I had a brief discussion with the whips yesterday and it will be a whipped vote against Dr Evan Harris's bill.
"I understand their argument is that there are financial constraints. They are saying we haven't got the money for the infrastructure to deal with it.
"It is like saying we have got a gold mine but we are not going to do anything because we can't afford a shovel. I think it is frankly ridiculous."
Mr Pound said his interest in the issue was personal. His younger brother died last month but his healthy organs could not be used because he was not carrying a donor card.
He added that one of his constituents, who suffers from cystic fibrosis, could die unless a suitable donor was found.
"It seems to me a crying shame, a tragedy, that the potential for saving lives is there and yet we can't actually bring together demand and supply," said Mr Pound.
"This really is a conscience issue and it shouldn't be a whipped vote."