The Labor stalwart was in Parliament when Ms Giddings first got in in 1996 and said her talent was immediately apparent.

"She's an old head on young shoulders - that's the first thing that struck me," Mr Lennon said.

"I think Lara was born to be premier."

Mr Lennon, who gave Ms Giddings her first ministry in 2004, said her election loss in 1998 had been unlucky after voters got Ken Bacon in Lyons confused with Jim Bacon and voted him in.

He said Ms Giddings's four years out of politics might have been a "blessing in disguise", allowing her to travel and work before being re-elected in Franklin in 2002.

Mr Lennon said he had seen first-hand how hard Ms Giddings worked and how talented she was.

"I've been a close colleague of hers. I'd like to think I've been a bit of a mentor (too)," he said.

"I have a lot of respect for her as a politician, as a social reformer."

Mr Lennon said she had worked in the health portfolio with "great distinction through difficult times", as well as stints in economic development, infrastructure and now treasury.

"I think she's ready (to be premier)," he said.

Mr Lennon also said David Bartlett's decision to step away from the top job to spend more time with his family should be respected.

He said he understood the pressures that being premier could have on a family, and the job affected everyone differently.

"He didn't have an easy run as premier because he had to deal with the global financial crisis," Mr Lennon said.

The difficult budget decisions Mr Bartlett had to make had affected the March 2010 election result.