Melbourne, Florida (CNN) – In the senior-heavy coastal city of Melbourne on Sunday, President Barack Obama, armed with a new study, continued to hammer the Republican plan to reform Medicare.

He highlighted a Harvard analysis, conducted by a former Obama adviser, that found seniors would pay more under the "Romney-Ryan plan," compared to his plan, which he said will strengthen the entitlement program.

Obama said GOP nominee Mitt Romney wants to "give money back to insurance companies and put them in charge of Medicare."

"Their voucher plan for Medicare would bankrupt Medicare. Our plan strengthens Medicare," Obama told a crowd of 3,050 gathered at a sports and recreation center. "No American should have to spend their golden years at the mercy of insurance companies."

The focus on Medicare on Sunday was the latest effort by the president and his campaign to turn up the noise around the program and throw Romney off his message on jobs and the economy, especially important as the president continues to make a play for the senior vote ahead of the November election.

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