Jeremy Corbyn has urged fellow Labour leadership hopefuls Yvette Cooper and Andy Burnham to remain in the race amid a row over who should be left standing to challenge the left-winger.
Corbyn, the leadership frontrunner, said: "I don’t think anyone should pull out, they’ve all been nominated, they are valid candidates."
He was speaking at a rally outside Kings Cross station, where he also discussed his policies to re-nationalise rail services in the UK, as Peter Kellner, the YouGov pollster, said there was no data on whether he is still ahead after the surge in membership and interventions from senior Labour figures.
“A week ago Jeremy Corbyn in my view was comfortably ahead. Is he now?, I don’t know,” the pollster told the BBC Radio 4's World at One.
Previously Kellner has said he would be “personally astonished” if Corbyn did not win. This time, he blamed two factors for the uncertainty of who is currently leading the race.
"Since that poll two things have happened, you’ve had that huge influx of new sign ups. And secondly we have had over the last week a run of 'grandee’s', one way or another, warning about Corbyn in victory and we don’t know what impact that is having on its electorates" he said.
Corbyn has come under increasing scrutiny since a YouGov poll for the Times put him in first place to win leadership, escalating competition between second place Andy Burnham and third Yvette Cooper. The pair's teams have traded blows in the last 24 hours over who is bet place to defeat Corbyn.
At his rally outside Kings Cross station, he slated and deflected the claims that either could drop out of the competition to overcome him: "If others want to debate arcane procedures, that’s up to them. We’re in this campaign because we have such huge levels of public support" he said.
In his speech, he outlined his campaign against rising railway prices, and argued privatisation has resulted in a "massive subsidy to many train operating companies".
"We have the most expensive railways in Europe, we have very hard working rail staff, we have a very good system but it needs to be fully integrated and I believe it should be publicly owned" he said.
Despite Kellner's comments, Corbyn's chances could have been bolstered by the rise in membership and around 190,000 have been recruited through trade unions, with between 90,000 and 100,000 thought to have come through Unite.