As the Prime Minister gets set to meet with US Donald Trump, National Party leader Simon Bridges said if she wants to be a "hero of the progressive left" she needs to push on the hard issues including climate change.
Yesterday, Mr Bridges released a statement saying Ms Ardern was "leaving behind a mess" as she heads off to Japan then the United Nations, but today he clarified he wasn't saying she shouldn't go on pre-planned trips.
"I'm simply making a point she does leave a mess behind," he told TVNZ1's Breakfast.
"I think the domestic agenda, if you can call it that, of the Government is in tatters and just getting on plane isn't going to change that."
However, Mr Bridges said meeting with US president Donald Trump, a world "superpower", was a good thing. He said if the meeting is to achieve anything though, Ms Ardern needed to push on issues that matter.
He said there was "a lot for her to advance" with meeting Mr Trump, adding if it was him he would raise climate change - which Mr Trump has previously called a "hoax".
"She needs to raise climate change if that's the nuclear free issue of our times."
He also said, "we're not going to get far if the United States isn't signed up to the Paris Agreement and clearly trade".
"I'm simply making the point that if you talk a big game on these things, if you want to be a hero of the progressive left in The Guardian and New York Times, around the world, you do have to raise these issues."
Mr Bridges said if it was him he would also discuss trade with Mr Trump, including talking about New Zealand's interests and how the US can play a larger role in the world order.
Yesterday Ms Ardern said she's "looking forward to discussing a wide range of international and regional issues with President Trump, including our cooperation in the Pacific and the trade relationship between our countries."
"The US is a key security partner for New Zealand, and an important trading partner."