Yvette Cooper is set to pull out of the race to succeed Jeremy Corbyn amid concerns she could struggle to win the support of party members.
The senior Labour MP indicated last month she would decide over Christmas whether to make a second bid for the leadership.
The former cabinet minister fuelled speculation she would run by warning at the weekend that Labour must resist “pressure to be a factional or narrow hard-Left party”.
But Ms Cooper, who served under Gordon Brown and Ed Miliband but refused to be in Mr Corbyn’s shadow cabinet, is expected to confirm she will not run over the next few days.
A friend told the Mirror: “The party membership is currently looking for someone that was part of Jeremy’s shadow cabinet, rather than somebody who has been in the actual cabinet under Gordon Brown.”
A second source told the Mail: “From the way Yvette is talking, she is not going to stand.
“The way the party is now, it is going to be very difficult for anyone who has criticised the Dear Leader, as she has.
“It’s ridiculous when he’s just lost us another election. It’s also a crying shame. Yvette is one of the few grown-ups we’ve got left – she’s probably our best chance.”
It comes after the first poll of Labour members suggested shadow Brexit secretary Keir Starmer would win a run-off against Corbynite favourite Rebecca Long-Bailey.
Shadow Brexit secretary Emily Thornberry and shadow Treasury minister Clive Lewis have already announced they will run.
Other names, including prominent Labour backbenchers Jess Phillips and Lisa Nandy, are expected to confirm they are running this weekend.
