Former Europe minister Caroline Flint has said she will defy Labour's three-line whip over tonight's Repeal Bill vote, insisting blocking it would cause "huge problems".
Although she campaigned to Remain, the Don Valley MP has backed her constituency's Leave vote since last summer and this morning repeated that she believed in "respecting the outcome of the referendum".
Speaking on the Today programme this morning, Flint said it was "Labour's job to improve this bill, not kill it as it begins its passage through parliament".
She added: "Whoever was in government would have to have a bill like this begin its journey, and I do believe it's our job to improve this bill - it certainly needs improving.
"But if we were to vote this bill down, if we were somehow to get the votes to kill it, that would cause huge problems, because it would end the session of parliament, we would probably have to prorogue, and they would have to come back with a new bill."
Labour issued a three-line whip on the EU Withdrawal Bill, also called the Repeal Bill, last week . The opposition party said it respected the outcome of the referendum, but was concerned the bill itself "would let government ministers grab powers from parliament to slash people's rights at work and reduce protections for consumers and the environment".
The bill is being debated again today ahead of a vote at midnight.
Both Prime Minister Theresa May and David Davis have issued personal pleas to MPs to vote the bill through at this stage. Despite concerns from both sides of the house that it amounts to a "power grab" it is widely expected that it will pass, with Remain-backing Tories so far saying they will rally behind the PM.
Clearly the government recognises how tight the vote will be. All leave has been cancelled, while MPs have been encouraged to stay in £150-a-night hotels or use taxis to get across London, to get the numbers up, The TImes reports.