National MP Nikki Kaye has launched an attack on her former opponent in the Auckland Central seat, saying she's all show and no substance.
"I've been in Auckland Central for eight years, and I struggle to name anything Jacinda has done", she said in Parliament on Wednesday afternoon.
Ms Kaye says Labour deputy leader Jacinda Ardern failed Generation X and Y by not supporting a rise in the Superannuation age.
She also criticised Ms Ardern for her public image, saying she will do "a whole lot of photo ops".
"She'll be across every billboard, but she absolutely failed our generation on her first day in the job."
Ms Ardern was surprised at the attack.
"It's certainly not a style of politics I've seen her use before.
"Nikki and I have run against each other in Auckland Central for a number of years and usually pretty much stuck to the issues and avoided making it personal. I'm going to stick to that.
"I'm going to stick with the way I like to do politics, and it's making sure that you keep away from making it too personal. But each to their own."