MIAMI — Two Florida doctors who received the nation’s highest Medicare reimbursements in 2012 are both major contributors to Democratic Party causes, and they have turned to the political system in recent years to defend themselves against suspicions that they may have submitted fraudulent or excessive charges to the federal government.

The pattern of large Medicare payments and six-figure political donations shows up among several of the doctors whose payment records were released for the first time this week by the Department of Health and Human Services. For years, the department refused to make the data public, and finally did so only after being sued by The Wall Street Journal.

Topping the list is Dr. Salomon E. Melgen, 59, an ophthalmologist from North Palm Beach, Fla., who received $21 million in Medicare reimbursements in 2012 alone. The doctor billed a bulk of his reimbursements for Lucentis, a medication used to treat macular degeneration made by a company that pays generous rebates to its doctors.

Dr. Melgen’s firm donated more than $700,000 to Majority PAC, a super PAC run by former aides to the Senate majority leader, Harry Reid, Democrat of Nevada. The super PAC then spent $600,000 to help re-elect Senator Robert Menendez, Democrat of New Jersey, who is a close friend of Dr. Melgen’s. Last year, Mr. Menendez himself became a target of investigation after the senator intervened on behalf of Dr. Melgen with federal officials and took flights on his private jet.