TAMPA — It is the white whale of downtown real estate.

For three decades, city leaders have chased a deal to buy ConAgra Food Inc.'s flour mill at 110 S Nebraska Ave. Built in 1938, it's one of the last remnants of downtown's industrial past, a squat factory sorely misplaced amid the new high-rise towers.

It may also be the key to unlocking the future of the Channel District, where groups tied to Tampa Bay Lightning owner Jeff Vinik have gone on a land-buying spree around his crown jewel, the Tampa Bay Times Forum.

Vinik is also vying to buy and remake the struggling Channelside Bay Plaza retail and entertainment complex. But whatever his plans for the district — his representatives have denied they include a baseball stadium — they would surely be easier to execute with the ConAgra property available than without.

"It's a very pivotal piece of land," said former Tampa Mayor Dick Greco, who said he once wanted to put a casino there. "It will make a big, big difference in whether there will ever be a stadium or anything there."

But the ConAgra property isn't just some empty industrial parcel. It holds an 80,000-square-foot factory that operates 24 hours a day and employs more than 35 people. They ship 1.5 million pounds of flour daily to bakers across Florida, the Southeast and the Caribbean.

"That plant provides the bulk of the flour for a lot of the bakeries that make our Cuban bread," said Tampa Mayor Bob Buckhorn.

One possible solution, however, may far exceed the $3 million value of ConAgra's factory and 3.4 acres: Help the Fortune 500 company build a new mill — at the cost, perhaps, of tens of millions — elsewhere in Tampa.

Then the old one could be plowed, freeing the area for a transformation.

"It's not as simple as taking the equipment and moving it somewhere else," said Tampa economic opportunity administrator Bob McDonaugh. "They would have to build a new plant somewhere else. It's a relatively expensive proposition."

ConAgra Foods is a conglomerate that employs 26,000 and is home to brands like Chef Boyar­dee, Peter Pan and Slim Jim.

Buckhorn said he supports the city, county and other government entities dedicating public resources to help smooth a deal. For example, he said the Tampa Port Authority owns plenty of land near railway lines that a new mill would need to bring in shipments of grain.

"I think it would make sense for a lot of reasons," said Buckhorn, who sits on the port's board. "It would keep jobs and a great corporate citizen and potentially move them to a location that allows them to be more productive.

"I think it would be a win-win for everybody if we could find a way to make this deal work."

In July, company representatives met with the mayor and city officials to make sure security for the Republican National Convention would not impede trucks. During the meeting, the mayor said the company seemed amenable to moving.

"I think they recognize their long-term future is not in downtown Tampa," Buckhorn said, "that development has basically encircled them and that they could do what they do better somewhere else. There would have to be an accommodation, a new plant could be found. But they've been very open to conversations."

ConAgra spokeswoman Becky Niiya confirmed that the company is contemplating a move.

"We realize that the city has grown up around our mill," she wrote in an email. "As the city prepared for the (RNC), this provided an opportunity for ConAgra Foods representatives to visit with city officials and other interested parties on the possible relocation of our mill site."

Buckhorn believes the ConAgra property is the key to redeveloping downtown partly because of the CSX railroad line that runs through the Channel District, serving the flour mill.

The land under those tracks was bought by the Tampa-Hills­borough County Expressway Authority in 2003 to expand N Meridian Avenue and build the reversible express lane on-ramp. But under the agreement with CSX, if the flour mill disappears, so do the railroad tracks along the property. Freeing up ConAgra's 3.4 acres would also free up the Expressway Authority's 6.5 acres just east of the factory. The land could then also be sold. All of that property sits north of the 12 acres that partnerships linked to Vinik have purchased in the past two years between ConAgra and the Times Forum.

"Without ConAgra there, you don't need the CSX line," Buckhorn said. "If the railroad wasn't there, then you could develop it."

But it would be hard to imagine Vinik or anyone else spending millions to build new restaurants and hotel rooms and condos — much less the mythical downtown Tampa baseball stadium — next door to a flour mill serviced round-the-clock by semitrailer trucks and trains. Why else would the land around the mill sit barren to this day, giving hockey fans a place to park?

And building ConAgra a new factory could add tens of millions to the price tag of a new baseball stadium that already would cost hundreds of millions — money no one seems to have.

"You know how Moby Dick ended," said Warren Weathers, the county's chief deputy property appraiser. "Be careful."

Times researcher John Martin and staff writer Jeff Harrington contributed to this report.