New speculation swept Canberra last night that Simon Crean was being pushed by senior Labor figures to offer himself as as a candidate to replace Prime Minister Julia Gillard.

Senior ministers described the atmosphere across the Labor government as feverish, and one told Fairfax he wouldn't be surprised if a leadership ballot was forced on caucus before the end of the week.

A spokesman for Mr Crean said there was ''no substance to the reports''.

However, another senior figure pointed out that if Ms Gillard's position deteriorated to the point she felt it necessary to throw open the leadership and Mr Crean's name was put forward, Kevin Rudd would immediately nominate.