Bill Shorten says he hasn't decided whether he wants to become federal Labor leader.
"I'm certainly not resolved about what should happen," Mr Shorten told ABC television on Sunday.
"I'm genuinely undecided."
Mr Shorten says he needs to talk to his family about whether or not to throw his hat in the ring.
Kevin Rudd said he would relinquish the Labor leadership after losing the prime ministership to Tony Abbott in Saturday's election.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Mr Shorten is one of several Labor MPs thought likely to replace him.
Mr Shorten said it was a very difficult decision when he switched his support from Julia Gillard to Kevin Rudd earlier this year.
But he believed it was justified because it helped Labor hang on to some key seats.
"I believe it had the effect of improving Labor's electoral fortunes," he said.
"But there's no doubt the Australian people have still marked us down for talking about ourselves and being too divided."
Mr Shorten said that despite the divisions, Labor had achieved a lot during its almost six years in government.
"We will not allow the conservatives to steal the last five years and pretend it didn't happen," he said.
