The press secretary described as an "emotional, junior staffer" by the National Party leader Simon Bridges has formally resigned.
In the immediate aftermath of the Christchurch mosque shootings, National's petition opposing the United Nations Migration Compact was removed from the party's website.
It had argued that the UN compact treated legal and illegal migration the same and restricted New Zealand's ability to make independent policy.
Media were initially told the party had removed it some weeks before as part of a regular archiving process.
However, the following week Mr Bridges told reporters an "emotional, junior staffer" had taken the petition down without the knowledge of others, in the hours after the shootings.
RNZ understands that resulted in a dispute between the staffer and the party leadership about exactly what had happened, and over Mr Bridges' comments.
The staffer in question was a long-serving press secretary for the National Party, including having worked for ministers in the previous government.
A spokesperson for the National Party said the staff member had resigned from his employment with Parliamentary Service.
"While we would have welcomed him staying, we respect his decision to resign and wish him well in his future endeavours", she said.