New Zealand will commemorate the first anniversary of the Christchurch mosques terror attack without a promised second tranche of gun law reform in place.

Legislation to establish a national firearms register, new licensing requirements and bulked-up penalties for non-compliance has stalled on its way through parliament.

In the aftermath of the 15 March atrocity, the prime minister, Jacinda Ardern, moved swiftly to pass laws to ban semi-automatic weapons and introduce a gun buyback scheme.

However, the second round of reform is stuck, falling short of the impressive bipartisanship that carried the first round of changes.

Ardern denied being disappointed at the bill’s sluggishness.

“The most important thing is we will have those substantial changes made to our gun laws,” she said. “We will be safer as a nation because of it and that will be done soon.”

The Police Association is firmly in support of the changes, which it says should have come into effect three decades ago following a mass shooting in Dunedin.

The association’s president Chris Cahill said the law’s passage was a “life or death matter”.

“We just have to get these guns off the streets and a firearms registry is a major component of that,” he said. “It was extremely encouraging to see the political symmetry in firearms reforms in the days after the Christchurch mosque shootings last year.

“But it is now obvious that lobbying and election-year politics have taken their toll on that resolve, at a time when we can least afford it.”

While the first round of reform passed the parliament almost unanimously – only the one-man libertarian ACT party opposed it – the second round has fallen well short of consensus.

Since the bill’s tabling in September, the opposition National party has flagged concerns, meaning all three government partners must support it for it to become law.

The delay can at least partly be attributed to negotiations between government coalition partners NZ First and Labour. The NZ First leader and deputy prime minister, Winston Peters, said negotiators remained a “work in progress”.

“We’ve still got things to negotiate and we’re working on them as we speak,” he said. “Our major concern is to ensure the law works, that it’s fair and that it lasts. We’re not very far away from getting to that.”

While neither Ardern nor the police minister, Stuart Nash, who has carriage of the legislation, is on record giving a firm deadline for the law changes, there’s little doubt they would have preferred the law in place ahead of Sunday’s anniversary.