Labour's secret weapon and superstar Jacinda Ardern has already leapfrogged her leader in the popularity contest.

The latest Newshub Reid Research poll has deputy leader Ms Ardern on 10.5 percent in the preferred Prime Minister stakes, more than 2 points higher than leader Andrew Little, who is on 8.3 percent.

Mr Little isn't shaken by his deputy's meteoric rise, saying he's not threatened or intimidated by her blossoming appeal with voters.

"It doesn't scare me. It doesn't make me feel awkward," he told Newshub.

"I'm very pleased we have a deputy leader who is as popular as she is."