WEST PALM BEACH, Fla. - President Obama slammed Mitt Romney's Medicare plan today, telling seniors in the battleground state of Florida that his rival's proposal would force them to fend for themselves and hurt them financially.

"He plans to turn Medicare into a voucher program," the president told a rowdy crowd at Century Village. "Understand how that works. If the voucher isn't worth what it takes to buy health insurance in the private marketplace, you're out of luck. You've got to make up the difference. You're on your own.

"Florida, that is wrong. It's wrong to ask you to pay more for Medicare so that people who are doing well right now get even more," the president added. "That's no way to reduce the deficit. We shouldn't be squeezing more money out of our seniors. My plan is to squeeze more money out of the health care system that is being wasted."

The president is hammering his opponent's plan during his two-day tour of the Sunshine State, where seniors make up roughly 17 percent of the population.

Obama received a warm welcome from the boisterous crowd of roughly 700 supporters, whom he described as "kind of wild." Taking to the stage, the president joked "that's the most kisses I've gotten at any campaign event."

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The Obama campaign sees the Medicare debate as particularly salient to the 3.4 million Floridians who are beneficiaries in the program and one that gives him an edge in the race against Romney.

Democrats have been warning seniors that Romney and Republicans want to "end Medicare as we know it."

"Seniors need to know what's at stake, and we're going to remind them of that," campaign spokeswoman Jen Psaki told reporters on Air Force One of Obama's message in Florida.

Yet, Romney has argued that it's Obama's management of Medicare that effectively ends the program as it's now known, claiming he has failed to address the program's solvency over the long term.

The presumptive GOP nominee has called for limiting the federal government's contribution per beneficiary to a fixed amount, indexed to inflation and income - something Democrats have dubbed a "voucher." Romney has said consumers can choose traditional Medicare or a private plan, infusing competition into the system and potentially lowering prices.

"Mitt Romney has a plan to preserve Medicare for today's seniors while strengthening it for future generations," said Romney policy adviser Lanhee Chen. "[Obama] takes hundreds of billions of dollars from Medicare to spend on Obamacare and will leave seniors with fewer choices."

Obama argues that cost-control measures imposed under the Affordable Care Act will reduce the amount of federal dollars needed for Medicare while preserving benefits; the administration also says those steps will extend Medicare's solvency through 2024.

This post has been updated.