Miami city officials have quietly upped the political bar on a plan to build a professional soccer stadium in downtown Miami.

An investment group backed by retired soccer superstar David Beckham is considering the possibility of filling and then building over a city-owned deepwater basin known as the Florida East Coast Railway slip next to Biscayne Boulevard just north of the American Airlines Arena.

The group has been looking at that site, which would require voter approval for a long-term lease or transfer, since opposition arose to their preferred site on PortMiami’s southwest corner.

A resolution to be presented at Thursday’s City Commission meeting would require another referendum if promised improvements granted through a major lease do not materialize within four years.

The Beckham team has still not said if the FEC slip would be feasible but promised a statement on the matter next week.

After Miami Mayor Tomas Regalado was quoted in the Miami Herald noting a voter referendum would be a must if the downtown site is sought, an adviser to Miami Beckham United, John Alschuler, said the group would “seek and fully support a voter referendum” if they went with the site.

It’s unclear if Miami Beckham United would support a four-year timeline once any deal is cut.