Veteran left-wing MP Jeremy Corbyn received the warmest welcome of all the candidates at a Labour leadership campaign hustings.
All three of his rivals were booed and heckled on the issue of renewing Trident, and for refusing to condemn Tory welfare reforms.
The line up of candidates vying to become the leader of the Labour Party will be finalised at midday, when the deadline for nominations passes.
Currently, shadow health secretary Andy Burnham, shadow home secretary Yvette Cooper and shadow health minister Liz Kendall, are all in the race, each having received at least 35 nominations from other Labour MPs.
However, dozens of the party's 232 current MPs are yet to declare their support, and left-winger Jeremy Corbyn, who is currently 13 short, might yet force his way into contention.
Once nominations are over, candidates will take part in a series of debates in marginal seats Labour failed to win this year all around the country. The eventual winner will then be voted on by members of the Labour Party as a whole, and announced on 12 September.
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.