Since the St Davids bid was mentioned in cabinet last month a partnership of ten different organisations has agreed that the bid should include St Davids and the Hundred of Dewisland which takes in Solva and Fishguard together with the coast and hinterland between.
The bid will be jointly led between Pembrokeshire County Council and St Davids City Council and will be considered by Pembrokeshire Coast National Park Authority later this month.
Of the potential £5 million capital investment, there is an expectation that half of it would be funded by the county council, with the other half coming from public and private partners.
The Heritage Lottery Fund has pledged to give £3m to the 2021winning city. It is estimated the accolade has benefitted the local economy of this year's City of Culture, Hull, to the tune of £60m.
Although there was general support for what council leader, Jamie Adams, called "quite an exceptional item" councillors also expressed their unease about the financial outlay the bid could involve.
"We are having to make really difficult decisions about our budget. It's heart breaking," said Councillor Sue Perkins. "I can't agree to something that is going to use so much funding when we are cutting down funding for a lot of our vulnerable people."
Councillor Rob Lewis added that he was "not 100 percent committed to the funding but 100 percent committed to the concept."
Chief finance officer Jon Haswell, said that that the £5 million capital funding would come against a backdrop of unknowns in terms of 21st Century Schools band B funding, the Swansea Bay City region and local government reorganisation.
He said that the £800,000 revenue funding would have to come from earmarked reserves.
"The only reserves with that sort of money in them are the invest to save reserve and service transformation reserve," he said. "If we take £0.8 million from those reserves that could have an effect on the transformation programme."
Deputy leader Keith Lewis, however, said that the bid was a once in a lifetime opportunity and that the council should commit itself 100 percent to the journey.
"To me and I think to people who look to the future of the economy of Pembrokeshire this is must," he said. "Pembrokeshire deserves to be put out there. The journey itself will provide huge publicity for our county. It's a totally unique bid and I feel we must commit to this investment for the sake of the county."
Seven cabinet members agreed to director of development, Steven Jones', recommendation to approve a £5 million capital guarantee to support the City of Culture 2021 Stage 1 application and to approve a £0.8m revenue contribution (from reserves) over a four year period.
One councillor abstained and one voted against.