A massive 621,000 square-foot "umbrella" that would shield fans from rain is the centerpiece of a proposal unveiled Thursday to upgrade the Miami Dolphins' home for future Super Bowls.

No price tag was put on the open-air covering or other improvements for Dolphin Stadium. Also left unaddressed was the question of who would pay for it, as officials explore various options to have public funds underwrite at least part of the bill.

"This is not a plan that has been priced out," Dolphins CEO Mike Dee told a South Florida Super Bowl Host subcommittee appointed to review the proposal. "We're not at a point where we've figured out financing or figured out how to make it work. But we want to leave no stone unturned to see how we can work it out."

NFL owners will vote in May on the 2014 Super Bowl host, as South Florida competes against Phoenix, Tampa and a new Meadowlands facility near completion for the New York Giants and Jets.

"I know there are other cities ready; they're up and running," host committee chairman Rodney Barreto said. "If we walk in there and say we're kind of yes, kind of no _ we're going to fall to the bottom of the line."

Funding could be sought from the state, or various combinations of city and multi-county funds. With many events also taking place in the Fort Lauderdale area, Broward County also receives a significant slice of the game's economic impact.

It could be a difficult sales pitch, though, in tough economic times with an electorate that historically has turned thumbs-down to stadium tax initiatives. Dolphins owner Stephen Ross and former owner H. Wayne Huizenga privately footed the bill for some $250 million in improvements to land next month's game.

"This doesn't make money for the Dolphins," said committee member Dick Anderson, the Dolphins' Hall of Fame safety and former host committee chair. "People need to realize it's in the community's interest to have major sports events in South Florida."

Dolphin Stadium's proposed roof would be a steel-and-metal suspension structure built over the seating area and concourses, leaving the playing field still exposed to the elements.

"We need to look at this less like a roof and more like an umbrella," Dee said. "It's going to let a lot of light through. It won't be a dark facility."

Seattle's Safeco Field has a similar concept, and Dee noted the proposed design has been used for a handful of European soccer stadiums.

The proposal is in response to suggestions from NFL commissioner Roger Goodell that the 23-year-old facility _ known as Land Shark Stadium until a sponsorship deal expired Wednesday _ needs upgrades to stay competitive in bidding for future Super Bowls.

South Florida will host the Super Bowl for a record 10th time on Feb. 7, its fifth visit to Dolphin Stadium. The game's last venture to the region, though, left folks all wet three years ago.

Torrential rain pelted the stadium area not long before kickoff, leaving fans who paid an average price of $800 scrambling for shelter. TV cameras showed large sections of empty seats that evening.

Dallas will stage next year's Super Bowl in its new $1 billion Cowboys Stadium, now completing its first season. Indianapolis, which also opened retractable-roof Lucas Oil Stadium this year, follows in 2012.