Six weeks from a possible countywide vote on a subsidized renovation of Sun Life Stadium, the Miami Dolphins still lack a crucial element for their pitch to the public: a deal.

The team’s plan to use local hotel taxes and state subsidies to fund part of a $390 million upgrade of the 1987 facility continued to move closer to state approval Wednesday, with a key Florida House committee endorsing a bill needed for the public dollars. And sources said county commission staffers were mulling a special meeting for early next week to schedule the referendum, which is expected May 14.

But with time running short to comply with public notice regulations for the vote, Miami-Dade Mayor Carlos Gimenez has yet to announce a deal with the Dolphins — much less reveal the financial details that will determine the ultimate cost to the public.

“We’ve got a lot of work to do,” Gimenez said this week. “It’s hard, but it’s doable.”

In recent weeks, Dolphins executives announced that Miami-Dade would not be asked to borrow any of the money needed for the upgrade, but instead would use a stream of new hotel taxes to help pay off the debt from the project over the next three decades. The Dolphins also said they would pay back Miami-Dade $120 million at the end of the 30 years, representing the county’s share of the $390 million construction tab.

One of the biggest questions remaining is how much of the new hotel tax the Dolphins want annually. County forecasts show raising mainland hotel taxes to 7 percent from 6 percent, as called for in the Dolphins’ bill, would generate about $690 million over 30 years. The Dolphins and Gimenez have been negotiating over how much of the tax should go to the team, with Miami-Dade’s largest hotel group advocating a portion go to tourism promotion.

A Dolphins spokesman said Wednesday it’s too early to say how much of the hotel tax the team would require for debt payments. “Any attempts by The Miami Herald to guess this number are premature,” Eric Jotkoff said. “The math is based on a series of assumptions that are just wrong, so the numbers are wrong.”

Sun Life already qualifies for $2 million a year from Florida’s pool of subsidies for new stadiums. The money is tied to the facility’s being retro-fit for baseball in 1994. That revenue stream expires in 2024.

A Dolphins-backed bill that passed its sixth legislative committee Wednesday would create a new subsidy for stadium renovations, which could give Sun Life an additional $3 million annually for 30 years. The new state subsidy would generate $90 million by 2044, and the Dolphins have pledged to pay back Florida $47 million at the end of the 30-year term.

Combined, all three revenue streams would generate $800 million over 30 years, based on Miami-Dade’s projection of hotel taxes growing 5 percent a year. The Dolphins have agreed to refund $120 million. That would leave a mathematical cap on the public’s cost at $680 million through 2044, with the big variable being how much of the hotel tax the Dolphins and Gimenez agree on sending to the stadium project. The actual total of the tax dollars being pursued by the Dolphins won’t be known until Gimenez and the team announce the specifics of a deal.

Details could be revealed at any moment, with people close to the Dolphins saying a deal with Gimenez is close. On Wednesday, the team’s top lobbyist, Ron Book, told lawmakers an agreement with the county would be announced “in the coming days.” Gimenez has made no such prediction.