Florida International University and Miami-Dade County have joined forces in an effort to resuscitate the shuttered, historic Coconut Grove Playhouse under a proposal submitted to the state of Florida, which took back ownership of the landmark theater last year.

The 13-page proposal, which is not yet fully fleshed out, could represent the last, best hope to keep the historic theater property in public hands and avert a sale by the state to the highest bidder.

Under the plan, the state would turn over the property to FIU, while the county would rebuild the deteriorated theater using $20 million in previously approved bond and bed-tax money. GableStage, a leading company now based at the Biltmore Hotel, would program, run and maintain the playhouse as a professional regional theater.

FIU’s theater program, meanwhile, would partner with GableStage to provide its students with training and hands-on experience in acting, directing, set and costume design and technical aspects of theatrical production. FIU could also use the playhouse for student productions, faculty lectures and public presentations.

The proposal was quickly drawn up and submitted to Florida’s Department of Environmental Protection, which manages state properties, to meet an April 15 deadline for state colleges and universities to put in dibs for the playhouse, which the state has declared surplus. The state had deeded the perennially debt-plagued playhouse to a nonprofit board in 2004, but exercised an automatic reverter clause in October to retake it after that group failed to make headway on plans to reopen the theater, which closed suddenly in 2006.

County administrators say they believe the plan represents a financially feasible approach that would ensure the playhouse becomes self-sustaining under the guidance of a successful nonprofit theater company. The fiscal linchpin would be income from the 2.5-acre property’s parking lot, which administrators say should be more than sufficient to cover any operating deficits.

Neither FIU nor the state would be on the hook financially, the proposal says.

“FIU is really trying to do a good deed here,’’ said Michael Spring, the county’s director of cultural affairs, while cautioning that “millions of details’’ remain to be worked out should the state approve the plan. “It’s not a deal; it’s an idea.’’

Among those details: a monetary claim by developers who had agreements with the former playhouse board to redevelop the property. The state says any entity receiving the playhouse property would have to satisfy outstanding debts.

“The debt isn’t necessarily erased if the property goes to FIU, so there needs to be meetings with state lawyers to find out what’s involved financially and legally,’’ Spring said.

Any proposal must be reviewed by Gov. Rick Scott and his cabinet, who together make up the state board of trustees. So far, a DEP spokesman said, FIU is the only institution to submit one. Under state rules, the property would be leased to FIU for $300 a year.

“If no other colleges or universities express interest, then the state board of trustees would review and, at their discretion, approve the business plan,” said DEP spokesman Patrick Gillespie.

If they don’t, the DEP must then offer the property for sale to a county or municipality at the appraised value. Should none be interested, the playhouse would be put up for bid.