Town hall chiefs have been warned the cost of running a new museum could fall on residents if the venture fails to attract enough visitors.
Blackpool Council has applied for a £15m Lottery grant towards opening the Blackpool Museum inside the Pavilion Theatre and Horseshoe at the Winter Gardens.
The project will cost £25m in total.
But Tory councillors have warned the attraction must be sustainable if it is to go ahead.
Coun Paul Galley told a full meeting of the council: "My worry is will we be left with something the council will have to subsidise as the novelty wears off and we are left with the hard grind of running a visitor attraction."
He called for councillors to be shown a full business plan, and added "without that level of scrutiny we are going to be left with something that is a chain around our ankles."
Conservative group leader Coun Tony Williams said he was worried about the impact of the museum on existing events held at the Winter Gardens.
He said; "The museum seems to be shrinking every day and it doesn't seem to be stacking up.
"How much is it going to impact on the Punk Festival, the Pigeon Show and the Dance Festival where merchandise is sold in the round?"
But council leader Coun Simon Blackburn said it was down to the experts, including from the Lottery Heritage Fund, to decide whether the project would succeed.
He said: "If it works we will do it, if not we won't but I would rather let the experts decide.
"If the council tax payer is required to subsidise the museum, then there won't be a museum."
The council has already committed £2.24m to the project, of which £1.2m has been spent as part of the development phase, with £1.5m of earmarked funding from the Government Growth Deal.
This leaves around £8m to be found from various sources including charitable donations, philanthropy and other grant sources.
It is proposed to give free admission to the museum to Blackpool residents.
A business plan has been developed which assumes a contribution from the council to the museum of up to £120,000 per year.
The museum is projected to attract 270,000 annual visits with a £2m turnover. In terms of economic benefit the project is expected to create an annual economic boost of £12.3m with the creation of 384 additional jobs, 40 as part of the museum.