The Labour MP for Neath, Christina Rees, has confirmed on Twitter she will not be in Sir Keir Starmer's front bench team.
Ms Rees, who had been shadow Welsh secretary since February 2017, tweeted: "I’ve just spoken with Keir about his plans for a new-look shadow cabinet and shadow Wales team.
"While sad to not be part of it, I understand completely Keir’s decision. I will now get behind Keir 100% from the backbenches".
Her replacement has not been announced. Sir Keir is currently forming his shadow cabinet and is expected to confirm appointments during the day.
On Sunday, Torfaen MP Nick Thomas-Symonds was named as shadow home secretary.