The prime minister says changes announced Monday aimed at improving transparency around lobbying at Parliament are his own initiatives, but the issue needs to be discussed more widely.
A refreshed Cabinet Manual will also be published later this month, setting new expectations for ministers in relation to their conduct and decisions when considering future employment, and Hipkins called on third-party lobbyists to sign up to a voluntary code of conduct.
He said the "programme of work" on the transparency issue would report back after the election "to whomever the government is" so further progress could be made.
The moves come after reporting by RNZ revealed the revolving door between government and lobbying firms.
Hipkins told RNZ's Guyon Espiner on Morning Report he did not necessarily think lobbyists got preferred access to politicians by having swipe card access to Parliament, but acknowledged a "perception challenge" existed.
"A lobbyist having a swipe card gets them through the front door without having to go through security, it doesn't guarantee them an appointment to meet with people... but I think there is a perception issue there, and so we're now just putting them onto the same footing as every other New Zealander who wants to come and meet with somebody at Parliament."
Any further changes in the transparency space would require a greater degree of consultation, he said, particularly when it came to the issue of whether restraint of trade clauses should be added to the contracts of officials in top government roles.
"I'm certainly open to that conversation though, I think that's one of the reasons we should get the policy work done on it," he said.
"Restraint of trade clauses - which is effectively what we would be talking about here if we were talking about staff members or top government officials - is something that we just need to pick our way through quite carefully."
He said there was typically some sort of monetary compensation involved when restraint of trade clauses were in play.
"You're potentially saying to someone that they can't apply their expertise in another way after they've finished a particular form of employment, and so I think we just have to work our way through that."
Hipkins' chief of staff Andrew Kirton previously worked as a lobbyist. His clients included the alcohol companies Lion and Asahi.
Hipkins said he was aware of the "higher-profile clients" Kirton had worked with in his previous role before he took the job as chief of staff.
"We were very, very clear when he took up the job that he would be severing all relationships with any previous clients that he had, and I'm absolutely confident and satisfied that he did that."
Chiefs of staff needed to have top secret security clearance and they played "a pretty pivotal role in terms of keeping the wheels of government spinning", Hipkins said, but he thought the power of the role could sometimes be "overstated".
"Ultimately, decisions that get taken in the prime minister's office are the responsibility of the prime minister, and I ultimately accept responsibility for the decisions that get taken in my office."
Hipkins said there had been attempts to reform the rules around lobbying in the past and he supported legislation proposed by the Greens in 2012, but "ultimately it didn't find favour of the then-government, who had the majority in Parliament and stopped it from progressing".
He said transparency was one of the most important tools that could be used "to make sure that people know what's going on and know who's speaking to whom and who is influencing whom".
The recent revelations that ex-Cabinet minister Stuart Nash had shared confidential Cabinet information with people who had provided him with financial donations were "not really" the reason Hipkins had begun looking into the issue of transparency, he said, though he acknowledged RNZ's reporting about lobbying had brought the issue to the forefront.
"Credit to you, Guyon, I think you've actually thrown more light on the issue in the last few weeks than there's been on it for some time," Hipkins said. "When these issues do come to light, I think government should respond in an appropriate way and I do think that there are some questions there that have been raised that do deserve a response."
'They shouldn't be hired by a lobbying firm the next day'
National deputy leader Nicola Willis told First Up the party wanted to see the "revolving door" between Parliament and lobbying firms closed.
"We support these first steps, but we'd like to see this taken further. In particular, National thinks there should be a stand-down period of 12 months after any minister leaves government; they shouldn't be hired by a lobbying firm the next day."
Willis said the party also wanted to see the establishment of a "transparent, publicly accountable register of who's doing the lobbying and who they're lobbying for".
"I think New Zealanders should feel that they have as much access to politicians as those lobbyists do, and National will be supporting the Speaker to remove that special access right, we think that makes sense."
She said very few people had the "enormous privilege and power" of being a minister of the Crown and some form of stand-down period would help to ensure transparency.
"I don't think it's too much to expect that ministers, having held those positions, with the extra salaries they entail, that they then, as a point of honour and integrity, have a stand-down period of 12 months."
Transparency initiatives 'largely symbolic' - academic
Max Rashbrooke, a writer and academic specialising in democracy and inequality, told Morning Report he was underwhelmed by the measures to improve transparency announced by the prime minister this week.
"I think the three things the prime minister's announced with immediate effect are largely symbolic or - in the case of voluntary self-regulation - unlikely to achieve anything much."
Hipkins' pledge to take a wider look at the issue and to potentially implement something comprehensive was promising, Rashbrooke said, "but that's a project that's going to take at least a year and there's no guarantee that anything definitive will come out of it".
While he was in favour of some form of stand-down period for those moving between government and lobbying jobs, Rashbrooke said work would need to be done to determine who that applied to and how it could be managed.
"All sorts of people in public life - ministers, but also MPs and senior public officials - hold very confidential public information and we need a mechanism to ensure they don't just go straight into the private sector and use that to the benefit of their private clients."
The chief executive of Transparency International's New Zealand branch, Julie Haggie, said the government's attempts to bring greater transparency to the lobbying industry were a good start, but more needed to be done.
"We'll be really happy when there's actual transparency occurring, when it's actually in place," she told Morning Report.
Establishing a public register people could search in order to find out which lobbyists were working for which companies would be a step in the right direction, she said, though the parameters of any such register would need to be carefully considered.
Australia had one, but it was quite limited in its scope, she said, "whereas the Canadian one has a lot more to offer in terms of public transparency and also scope of what is a lobbyist".