Still, Jackson’s patient numbers have been steadily declining since 2007, the year that UM bought Cedars Medical Center. Since UM doctors represent nearly 90 percent of the staff at Jackson Memorial, some believe that the timing of Jackson’s patient decline and UM’s purchase of Cedars was not coincidental.

“They’re a competing hospital,’’ Marcos Lapciuc, the immediate past chairman of the board that governs Jackson, said of UM. Lapciuc said that among Jackson’s biggest challenges is “UM’s hospital raiding us” for paying patients.

Another challenge for Jackson is improving its image in the community, so it is no longer considered just the hospital for the poor but the region’s leader in trauma services, transplants and specialty services.

“The Jackson story is not out there,’’ said Sharpton, the board chairman.

Jackson’s main hospital is Florida’s largest, with 1,500 beds, and it has long served as the backbone of Miami-Dade’s public healthcare. It serves hundreds of thousands of patients a year, and its Ryder Trauma Center is one of the first and considered among the best free-standing trauma hospitals in the nation.

Jackson is also, by far, the largest provider of indigent care, charity care and Medicaid services in Miami Dade, and is the single largest operator of Medicaid programs in the state.

But like a number of safety-net hospitals nationwide that provide charity care to uninsured patients, Jackson faces an uncertain future in light of Florida’s refusal to expand its Medicaid program under federal healthcare reform.

As part of the Affordable Care Act passed by Congress in 2010, federal government payments for hospitals that treat a disproportionate share of uninsured patients were supposed to be reduced by an estimated $17 billion between 2014 and 2020.

Migoya sees a bigger challenge ahead: Florida’s Medicaid reform, which is scheduled to take effect in 2014 and will move Medicaid beneficiaries into a managed care program that will allow insurers to compete for their clientele, forcing hospitals to negotiate lower reimbursements rates. He expects Jackson will lose about $100 million a year — another reason, he said, the hospital system cannot afford to delay the proposed projects.

Currently Jackson treats more patients on Medicaid — which reimburses hospitals at less than the cost of services —than any other plan.

In fiscal 2011, Medicaid accounted for 40 percent of all payments to Jackson for discharged patients, according to an independent valuation of the hospital system. Another 22 percent of patients were uninsured. About 21 percent were paid for by Medicare, and only 13.7 percent of discharged patients carried commercial insurance.

By comparison, only about 18 percent of patients discharged from Baptist Hospital of Miami were paid for by Medicaid, and 5 percent were uninsured. About 33 percent of patients discharged from Baptist Hospital were covered by commercial insurance, and an estimated 43 percent were on Medicare.

Jackson leaders believe that payer mix can change with the major capital investment they have proposed.

On Tuesday, Miami-Dade commissioners must decide whether to schedule the special referendum to hike the property-tax rate hike to finance the upgrades.