National MP Erica Stanford says the Government should have changed the rules around how ministers handle conflicts of interest "earlier".
Stanford's comments come after former Transport Minister Michael Wood resigned and revealed he held further shares which weren't properly declared.
On Wednesday, Prime Minister Chris Hipkins said he had accepted Wood's resignation after being alerted on Tuesday to additional shareholdings he held in a trust he is a trustee and beneficiary of.
The Prime Minister said the shares raised concerns about Wood not identifying and managing potential conflicts of interest.
Wood has faced weeks of scrutiny following his failure to properly declare shares he held in Auckland Airport.
He resigned after informing Hipkins he was also part of a trust which holds shares in Chorus, Spark, and the National Australia Bank.
The saga prompted Hipkins to make several changes around how ministers handle conflicts of interest.
Appearing on AM on Friday, National MP Erica Stanford said the party supports the changes, but they should have happened earlier.
"We are supportive of these changes and quite obviously they should have been introduced earlier because we are finding ourselves in a situation where, totally inexplicably, Michael Wood for three and a half years was told to declare his conflicts and never did," Stanford told AM co-host Laura Tupou.
"These rules definitely are needed. They'll be fondly dubbed the Michael laws" she added.
Stanford also said if National gets into power after the upcoming October election, all shares owned by any potential ministers should be divested "immediately."
"The best thing for all of us to do is get rid of all shares whatever we have - divest immediately, that's what Michael should have done."
Labour minister Ginny Andersen, who was appearing on AM alongside Stanford, said she thought the potential changes would be welcomed after the furore that cost Prime Minister Chris Hipkins his third minister in as many months.
"It's always good for democracy to be as transparent as possible so by having quarterly requirements and by doing them in person that puts in some extra protections to make sure everyone is being upfront about what their shareholdings are," Andersen said.
