In an email to THB, Mr Newman said through a staff member he wasn't available "to attend a meeting of this type which potentially involves a detailed discussion around the BOI final draft decision but he is happy to consider attending such a meeting after the final decision is released".
He said yesterday he had nothing to add to that response.
"We're in the middle of a process and once we're through that process, if we think it's sensible to have a conversation we'll do so," he said.
In an earlier email to Mr Newman, THB chairwoman Megan Rose asked him to reconsider attending given he was "the project's biggest advocate and influencer".
"There are simple things the public is struggling to understand about the dam and no one knows it better than you," she said.
But Mr Newman said yesterday the questions to be raised at the meeting could be met by regional council staff who would be attending.
"Other people attending that meeting are sufficiently well briefed to do that."
The council's chief executive, Liz Lambert, and its resource management group manager, Iain Maxwell, will be attending.
However Hawke's Bay Regional Council chairman Fenton Wilson has told THB he will not attend the meeting because he will be in his hometown of Wairoa today.