Starmer, a former director of public prosecutions in England and Wales, became an MP in 2015 and has served as shadow Brexit minister for three years, using his legal expertise to hold the government to account over its plans.

He is popular among the anti-Brexit and centrist factions of his party, but is less liked among those new members attracted to the party by Corbyn’s radicalism.

The 57-year-old would likely face a highly charged ideological battle to win over enough members.

Rebecca Long-Bailey

Starmer’s biggest threat appears to be 40-year-old Rebecca Long-Bailey, a Corbyn loyalist who has long been seen as his natural successor.

The daughter of a docker from Manchester, northwest England, Long-Bailey has the credentials to win back disaffected voters in the party’s traditional working-class heartlands, while maintaining the backing of Corbyn’s supporters.

A “continuity Corbynite”, according to University of Nottingham professor Steven Fielding, she is likely to have the backing of her outgoing boss, helping boost her reputation among the party’s membership.

But given the waning star of the veteran leftist leader, it is unclear how much influence he will have over the process.

She received a boost when one of her main potential rivals, Angela Rayner, was reported to have stepped out of the race to focus on becoming deputy leader.

The combative 39-year-old is a former flatmate of Long-Bailey, and describes herself as being part of Labour’s “soft-left” wing.

Her backstory has won admirers: she left school at 16, pregnant and without any qualifications, but worked her way up to become a senior trade union official.

Emily Thornberry

Corbyn’s foreign affairs spokeswoman for two years, the outspoken MP has previously courted controversy but could be a popular choice among the party’s “Remain” majority having been a vocal proponent of stopping Brexit.

Thornberry, 59, first appeared on the national stage in 2014 after tweeting a photograph of a house in a working-class constituency adorned with three England flags.

Then party leader Ed Miliband said the apparently mocking tweet showed a “lack of respect”, and the incident, over which she resigned, could still hinder her in her efforts to win working class support.

Lisa Nandy

Nandy, 40, said she will enter the race if she can find a way of “regaining the trust” of Labour voters who defected last week.

The native northerner made a thinly-veiled pitch for the leadership when parliament met on Wednesday, presenting herself as the champion of the working-class areas that turned blue.

She referenced the “communities that have just sent shock waves through the political system”, saying they saw parliament as a “bastion of privilege”.

Jess Phillips

The 38-year-old was elected to parliament in 2015 after a career working with refugees and victims of domestic violence.

She soon became one of its most recognisable voices, with passionate and energetic performances delivered in her distinctive West Midlands accent.

She is no friend of Corbyn, having once joked she would “stab him in the front”, and would be an outsider to replace him.

But she is a canny media operator, being one of the party’s most visible MPs on Twitter and earning glowing profiles in newspapers from across the political spectrum.