The bill would give police the power to apply for a High Court order for returning New Zealanders who have been involved in overseas terrorist activity.
The Green Party has thumbed its nose at the bill - calling it dog-whistling - which means the National Party's support is crucial.
Greens' MP Golriz Ghahraman said the party felt the bill was superfluous and could have unintended consequences.
"Our concerns are that this bill is, essentially, unnecessary. Our criminal law exists, our crime of terrorism exists, our police have powers to surveil people," she said.
"This bill captures people who've been convicted or deported from essentially anywhere in the world based on terrorism-type allegations.
"My home nation of Iran would consider a feminist activist a terrorist or an environmental activist a terrorist.
"We don't think that kind of law has application in New Zealand or should have."
The legislation would apply to the likes of Mark Taylor, the so called bumbling jihadi who joined ISIS and is being detained by Kurdish forces in Syria.
The National Party is supporting the bill through the first reading but leader Simon Bridges said he would then want to see changes including toughening penalties and making it apply to people as young as 14.
"I wouldn't put them as bottom lines inasmuch as I feel a deep sense of duty that we need to support this given the Green Party isn't and we need rules in place for the likes of Mark Taylor," Mr Bridges said.
"All of that said, though, I'll be strongly urging the government to take these. I think New Zealanders will be less safe if the changes National is recommending don't happen.''
But Mr Little said the National Party would have to live with whatever decisions it made.
"The problem for the National Party is if they want to withdraw their support after the first reading, then it will be they who are leaving New Zealanders unsafe. If they want to have that on their conscience then that's for them."
The bill would give police the power to detain people suspect are a threat on arrival into the country and put restrictions on them including who they can contact and their access to the internet, or even reporting to a police station regularly or wearing an electronic monitoring bracelet.
Ms Ghahraman said there's a huge risk the wrong people will be targeted by the law.
"What's actually frightening about this is we're going to rely on evidence collected by foreign agencies who may have employed torture which we know isn't going to be reliable, or actually targeted at political dissidents," she said.
Mr Bridges wants seven amendments to the bill including lowering the age of those it applies to from 18 to 14, increasing the maximum amount of time penalties can be applied and removing a financial penalty while increasing the imprisonment penalty for those who don't comply.
But Mr Little said lowering the age to 14 made no sense.
"To take the National Party argument to its logical extension, we should arrest pretty much everybody who crosses the border until we're happy they're not a risk.
"That is not an acceptable approach to take. What I don't want to see happening is when we take practical, logical measures to protect the safety of the New Zealand community that we don't give into some crude, mindless bidding war with the National Party who just want to show for some reason how much hairier-chested they are than us.
"That is not a useful debate to have.''
Mr Bridges disagrees.
"Regrettably there are young people who are radicalised by their family and by other people. In Australia they've seen examples of young people, as young as 15, who they've needed to have these sort of orders in place on.
"No one takes any pleasure in this but I think it's a situation where we need to have the scope at least for the High Court to go lower", he said.
But don't expect to see it happening on Mr Little's watch.
"I don't see a reason for it and in the absence of a good reason for it I can't see myself supporting that change,'' he said.
The only support Mr Little can rely on is New Zealand First leader Winston Peters - a strange twist of events given Mr Peters has twice been the thorn in Mr Little's side when trying to push through new legislation.
"Do you not understand that this is an attack on the whole Western civilisation that you're looking at? The reality is if someone came into this country and we didn't take the action we should have taken, when it's all over you'll all be looking at us and screaming 'blue murder' that we didn't act, Mr Peters said.
"Well we're getting in first, responsibly."
The bill will have its first reading in Parliament next week.
