Dr Broad said following the party's third straight election loss, it was clear something had to change, and took aim at Labor's powerful left faction.

"It's pretty clear that if we look at the election results, the Liberals won more than 50 per cent of the vote in seats like Braddon, Bass and Lyons," Dr Broad said.

"Even if we won every Independent and Greens vote, we still wouldn't have won the election."

RELATED: David O'Byrne has thrown his hat in the ring for Labor leader

This comes after opposition leader Rebecca White announced her decision to not re-contest her position. She has endorsed David O'Byrne for the position.

Dr Broad said his leadership bid was a "rallying cry" for moderate voices in the party and former Labor voters, directly addressing commentary that hard left factions have been leading the charge behind the scenes.

RELATED: Rebecca White confirms she won't contest Labor party leadership

"What's happening in the party is that the moderate voices have been silenced, and that has to end.

"What we can see is that, the hard left of the party, since they've been in control, we've lost seats and lost three state elections.

"Every time a moderate voice emerges, the hard left tries their best to silence them. We saw that during the election campaign with attempts to... block Dean Winter.

"(They've) rigged the rules that put the power of electing the leadership into the hands of these power brokers."

He said he was "disappointed" that Ms White endorsed Mr O'Byrne, but understood - hinting that Ms White's resignation came with a deal to secure a review.

"That's a choice she's made, and obviously I'm disappointed that she's done that, but she's been pushed out of the leadership. As we speak, they're dividing their spoils."

He said he didn't mind being the underdog.

"This is a debate we need to have, and by me standing, we will have it. This is too big not to try. I know the odds are stacked against me, but that's one of the things that needs to be exposed."

Dr Broad said that, if he wins the leadership, he will be calling for "immediate reform and national intervention".

On Sunday afternoon Mr O'Byrne confirmed his intention to also nominate for leadership.

"I do this in the knowledge that there is a big task ahead for Labor," Mr O'Byrne said.

"We have not been in majority government since 2006, and we have not been able to rebuild the relationship with the Tasmanian community that we would really like to.

"We need to be a party that is united and that is focused on the issues that the Tasmanian community want us to focus on."

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: