The potential tab for winning Super Bowl 50 continues to grow for Miami-Dade County.

Over the weekend, the Miami Dolphins switched gears and began pushing for a quick referendum on using public dollars for about half of a $400 million renovation of Sun Life Stadium. The team contends the upgrade is key to bringing the 50th Super Bowl to Miami Gardens in 2016. That game will be awarded by May 22, and the Dolphins want Miami-Dade to hold a special countywide election before NFL owners vote.

Holding a special election could cost as much as $5 million, county officials said, and the urgency tied to the Super Bowl contest is sure to put pressure on the Dolphins to compensate Miami-Dade for the expense.

“I’m not at all favorable to the idea of us paying for it,’’ County Commissioner Xavier Suarez said Sunday while describing himself as “heartened” by the Dolphins’ decision to endorse a referendum.

Dolphins executives were mum over the weekend on whether owner Stephen Ross would offer to pay for an election the team has previously resisted, or if they’re aware of a legal way to reimburse the county. Though racetracks paid Broward and Miami-Dade about $7 million as compensation for a 2005 special election on a ballot issue they wanted passed, state law generally bars local governments from taking money for an election.

The rush for a referendum marks a big pivot by a team that has resisted letting the public vote on public funding for Sun Life since it first began lobbying for government help in 2010. And it also puts even more of a spotlight on the potential rewards for hosting the 50th Super Bowl rather than the 52nd or 53rd, since a revamped stadium would probably make Miami Gardens a strong contender for future Super Bowls whenever the upgrade took place.

“It’s the golden anniversary game,” Rodney Barreto, chair of South Florida Super Bowl Committee and one of the Dolphins’ most vocal backers, said of Super Bowl 50. “It’s an opportunity that only comes along once in a lifetime.’’

If Miami-Dade had to pay for the election, it could dilute a central part of Ross’ campaign for the kind of tax support already in place at Marlins Park and the Miami Heat’s American Airlines Arena. In unveiling the proposed funding plan last month, Ross issued a pledge that the upgrades would mean no new expenses for Miami-Dade taxpayers.

Instead, $199 million of the costs would come from a new $3 million state subsidy for Sun Life and increasing the taxes hotel guests in mainland Miami-Dade hotels to 7 percent from 6 percent.

Ross, a billionaire real estate developer based in New York, has pushed back on calls for him to fund the entire renovation himself, given the $210 million in renovations the team paid for in 2007, the $1 billion he paid for the team in 2009, and the economic boost that goes to the region from a major sporting event.

On a program aired Sunday, WPLG-ABC 10’s Michael Putney asked Dolphins CEO Mike Dee to respond to criticism that the plan is “welfare for billionaires.” Dee answered: “Just because somebody is wealthy enough doesn’t mean he should invest money in a way that is unwise. Mr. Ross has made a tremendous commitment to this franchise, and to this community.”