Paul Ryan seems like the consensus candidate to be Republican Mitt Romney's running mate.

Republicans are happy.

But so are Democrats, who see Ryan’s plan to change Medicare as a toxic idea in Florida, a must-win state for Republicans, where retirees cast a suspicious eye on changes to government-retirement programs.

"Too good to be true,” said Democratic consultant and CNN commentator Paul Begala, according to CNBC's John Harwood.

In addition to talking more about Medicare and Republican plans to scale it back, Democrats won't have to face their nemesis, Sen. Marco Rubio, on a statewide ticket for the second election in a row in Florida, a state that Rubio could help deliver to Romney.

Ryan might do the opposite for the GOP ticket.

The Wisconsin Republican representative is the face and namesake of the so-called "Ryan Plan," which seeks to turn Medicare in the future into a “premium support” system to help seniors pay for private health insurance.

Democrats use the “V” word to describe it: Voucher. And they point to independent studies showing that  the voucher, a predetermined amount of money that escalates at a predetermined rate over time, won’t keep pace with medical inflation.

Bottom line: seniors would have to pay more out of pocket in the future than they’re paying now.

But Ryan and the plan’s defenders point out that nothing’s free. Someone’s always paying something out of pocket for Medicare. And on its current path, Medicare isn't sustainable. And more and more seniors are buying supplemental insurance to cover Medicare expenses now, making the system appear more voucher-like over time.

At least in the short term, Ryan’s selection will transform the presidential campaign into a policy-heavy discussion about the two biggest and most popular entitlement programs in Florida and the nation, Medicare and Social Security, which Ryan once wanted to partly privatize.

It’s a wonky policy debate that has no easy answer, relies on projections and guesses and seems laden with political calculations no matter how objective the issue might appear.

Rubio supports the Ryan plan and had said about as much in his successful 2010 campaign for U.S. Senate in Florida, a sign that talking future Medicare cuts and changes isn’t a third-rail of Florida politics. But it was a tea-party, Republican heavy year. This election, like most presidential contests in Florida, will bring out a disproportionately higher number of Democrats than in 2010.

Also, Rubio wasn’t the face of the Ryan plan.

Rubio appeals to Hispanic voters, especially Cuban-Americans, who comprise a little more than a third of the Florida Hispanic electorate. Polls showed he helped Romney earn higher support among Hispanics than any other potential vice-presidential pick.

Overall, Rubio gave Romney about a 2 percentage-point boost in Florida, according to the Miami Herald’s last poll. No other candidate does that.

Rubio’s popular in Florida. Ryan’s unknown.

And his plan probably isn’t popular in Florida, the nation’s biggest swing state with the biggest population of retirees and seniors. About 17 percent of the state’s population is older than 65; and seniors make up a disproportionately larger segment of the electorate.

Cutting Medicare isn’t popular. Just ask nearly every Republican who bashed President Obama’s healthcare plan for cutting $500 billion from Medicare over a decade.

Now Democrats are ready to repay the favor. They point out that independent analysts have concluded that future beneficiaries would end up paying more under Ryan’s plan than under the program as currently structured. A U.S. Senate study overseen by Democrats reported last year that out-of-pocket expenses would more than double in all states in 2022 under a Ryan-like proposal. But Florida's increase would be the highest, $7,383.

While no Florida-specific polls on the Ryan plan are available, a poll last summer by CNN/Opinion Research Corp. poll said that more than 50 percent of voters opposed Ryan’s proposal. Opposition was highest among senior citizens, even though the plan would affect only those 55 and younger.

A recent poll conducted for AARP of 500 Florida retirees and Baby Boomers showed that Romney and President Obama were virtually tied. Romney had the biggest edge with retirees – who wouldn’t be affected as much by the Ryan plan. But Baby Boomers were essentially deadlocked 45-46 percent over Romney and Obama.

And Baby Boomers were far more likely than retirees to worry about their retirement and healthcare. Most believed they would rely more on Social Security and Medicare than they previously thought.

Most Republicans get queasy talking about Medicare changes in a general election.

Before dropping out as a U.S. Senate candidate last year, Florida Senate President Mike Haridopolos balked when asked about the Ryan plan. His campaign pointed out that 55 percent of Florida GOP primary voters were older than 60. And the plan wasn’t popular with them.

The likely Republican Senate nominee, Connie Mack, had called the Ryan plan “a joke,” but his campaign later said he was referring to the process of votes in Washington.

Mack, like Romney, will have a lot more explaining to do about the plan in the coming months.