Senior party figures speculated Scott Morrison wanted to overturn the preselection for a new candidate.
The Queensland businessman said he will field candidates in all 151 lower house seats as he tries to rebuild his United Australia Party into a political force.
Close to 300 operatives are assigned to the campaign, as Bill Shorten prepares for a Queensland bus tour.
The former prime ministers are at war over Mr Rudd's call for a royal commission into News Corp's "campaign" against the NBN.
After narrowing in 2017, the gender pay gap blew out last year to an average of $3000 a year - or 4.8 per cent.