New York City F.C. and a major New York City real estate developer will submit a proposal to build a soccer stadium on property at Belmont Park ahead of a Thursday afternoon deadline. But the site might not be their first choice — and it is not their only one.

The Empire State Development Corporation, which controls the Belmont site, had issued a request for proposals from developers interested in the Long Island property, and it set a deadline of Thursday at 2 p.m. for submissions. The Islanders are also expected to submit a proposal to build an arena on the site.

N.Y.C.F.C., which plays in Major League Soccer, confirmed it would submit a proposal in partnership with the developer, the Related Companies, but refused to comment on its plans. A Related spokeswoman declined to comment.

“N.Y.C.F.C. is in very active pursuit of a new home,” the team said in a statement.

That pursuit apparently includes other options. N.Y.C.F.C., which currently plays home games at Yankee Stadium, and Related expressed interest earlier this year in an Empire State Development Corporation site at the Harlem River Yards, a 12.8-acre parcel on the Harlem River in the Mott Haven section of the Bronx, according to a person familiar with the discussions. And the team is investigating at least two sites in Willets Point, Queens.