Shadow Justice Minister Steve Reed backed The Sun’s campaign seeking justice for Jade Ward.
Her killer Russell Marsh can still have input in their four children’s upbringing from jail.
Mr Reed said: “It makes me sick that killers can get child custody.”
Jade’s family say their push to amend legislation has so far fallen flat across Whitehall.
But Justice Secretary Alex Chalk is understood to be looking at options to change the law.
Labour will put down an amendment to a Victims’ bill currently going through Parliament to address the issue.
A government spokesperson said: “This was a horrific crime and our thoughts remain with the family and friends of Jade Ward.
“Judges are required to put the welfare of children first and can effectively remove all rights and powers from a parent who has murdered the other.
“We have also asked the Family Procedure Rule Committee to look into also looking at how the processes for applying to restrict parental responsibility can be made simpler and quicker for families.”