Veteran Labour MP Barry Gardiner has told the BBC he is considering running for the party’s leadership.
The shadow international trade spokesman will make a decision whether to enter the race shortly, political editor Laura Kuenssberg said.
Candidates have until 13 January to win the backing of the 22 MPs and MEPs needed to get on the ballot paper.
On Wednesday, Sir Keir Starmer became the first candidate to pass this threshold, amassing 41 nominations.
He also won the backing of the UK’s largest union Unison, the first union to state a preference.
The other contenders to succeed leader Jeremy Corbyn are shadow business secretary Rebecca Long Bailey, shadow foreign secretary Emily Thornberry, shadow treasury minister Clive Lewis, Birmingham Yardley MP Jess Phillips and Wigan MP Lisa Nandy.
The party’s new leader and deputy will be announced on 4 April.
Mr Gardiner, who is currently on a trade trip to Abu Dhabi, has been MP for Brent North since 1997. He has served in Mr Corbyn’s frontbench team since 2016.
Unite union boss Len McCluskey dismissed claims he had approached Mr Gardiner about running because of his concerns about the chances of Mrs Long Bailey, who is regarded as the standard bearer for the left of the party.
Unite, Labour’s largest financial backer, has said it will not make a decision on who to back until later this month.
Mrs Long Bailey currently has 17 nominations, one more than Mrs Phillips. Ms Nandy has 12, Ms Thornberry three and Mr Lewis one.