Bill Shorten has told allies he wants to return as Labor leader, but is preparing to be denied his preferred frontbench positions as health or foreign affairs spokesman when Anthony Albanese unveils the opposition's new-look frontbench this weekend.

The former opposition leader used an address to MPs in Canberra on Thursday to pledge loyalty to Labor's newly installed leadership team and launch a stinging attack on corporate Australia and sections of the media over the party's shock defeat at the May 18 election.

"Rather than commentators' snap judgements, or hindsight masquerading as insight, it is important that we take our time to reflect," Mr Shorten said.

"But obviously we were up against corporate leviathans, a financial behemoth, spending an unprecedented hundreds of millions of dollars advertising, telling lies, spreading fear. They got what they wanted."

Mr Shorten has decided against moving to the backbench and will serve on Labor's frontbench in a move being widely interpreted by colleagues as a sign he still harbours leadership ambitions.