Napier Mayor Bill Dalton said the advertisement was an insult to Hawke's Bay residents, and its featured ideas were outside the province of local government.
"The whole wrap was an insult to people's intelligence," he said.
The items on the list which particularly offended him were "more fish in the Bay" - a call to petition central government to ban commercial inshore fishing in the region, and "cheaper flights" which suggested a unified council should negotiate more affordable air travel on the region's behalf.
"More fish in the bay? What a load of garbage," Mr Dalton said. "How are they going to put more fish in the Bay? Most, if not all, of these ideas are not in the province of local government. It's an attempt to con the people. "Cheaper flights - how are they going to bring cheaper flights to Hawke's Bay? Are they going to buy an aeroplane and go into competition with Air New Zealand?"
The ideas were not original, but were simply being used as "tokens" to prop up a marketing campaign.
"The whole A Better Hawke's Bay campaign is based on feel-good slogans, there's no guts to any of it."
In response, ABHB chairman Rebecca Turner said Mr Dalton's remarks were "unhealthy". The campaign had received 1200 responses from residents in five-weeks and Ms Turner was "absolutely thrilled" with feedback.
"Making unhealthy remarks about what people thought long and hard about is poor form," she said. "Unless we have a co-ordinated effort to lobby central government, which we do not have now, unless we have a regional plan, which we do not have now - then how do we expect to make a difference in Hawke's Bay?"
Wairoa Mayor Craig Little also expressed his anger at the campaign. "They've got no understanding or comprehension of what local government does," he said of the lobby group.
"To end off saying there's going to be more fish in the Bay, that's like saying we're going to tell Lotto to draw the winning powerball in Hawke's Bay every third week."
One of the items on the list in the advertisement, titled "Grow Northern Hawke's Bay," suggested sealing State Highway 38 to open up Lake Waikaremoana and Mahia to more tourists.
"We're already working with NZTA to take over the running of State Highway 38," Mr Little said. "They've got no idea what we're doing up here. These guys have enough money to throw at an advertising campaign, and we're just like poor cousins up here in Wairoa."
Central Hawke's Bay Mayor Peter Butler said the campaign wasn't backed up with facts.
"The one that stands out is more fish in the sea - where did they get that? From what I can see, they've gone overboard."
He said Central Hawke's Bay was already in the process of becoming a food production powerhouse, which was "proof we don't need to amalgamate".
Hastings Mayor Lawrence Yule was the only mayor to defend the advertisement, saying it simply contained a list of "aspirational goals" from the people of Hawke's Bay.
"These are what the people of Hawke's Bay want, and actually if you stand back from them, I don't think you can disagree with any of them," he said.
The "more fish in the Bay" idea could be realised if leaders lobbied on behalf of residents.
"It may not be in the province of local government, but local government is meant to represent the people, and actually leaders here need to advocate on behalf of the people," he said.
He believed amalgamating the region's authorities was the most viable way to realise the ideas featured in the advertisement.
Hawke's Bay residents will have their say in a referendum. Voting closes on September 15.
