Clearly, Democrats think the “Buffett Rule” is very good politics.

President Obama is pitching it in Boca Raton, Fla., today — his 20th speech on the subject since the State of the Union, according to CBS. Yesterday, his campaign held a conference call about it. Vice President Biden will talk about it Thursday in New Hampshire. Senate Democrats have pledged to push it all year long.

But a new survey from a centrist Democratic group suggests that the proposal, which would ensure that taxpayers who make over $1 million pay at least a 30 percent rate on all their income, might not be campaign magic.

Berkshire Hathaway Chairman Warren Buffett wanders the company trade show before the company's annual meeting in Omaha April 30. (Rick Wilking/Reuters)

The Third Way poll found that up-for-grabs independent voters in swing states “prefer an optimistic, opportunity framework on the economy over one based on fairness and income inequality” by 51 to 43 percent. A supermajority of these “swing independents” say the system is already basically fair. The deficit is a bigger priority than income inequality.

Even though this group currently leans towards Obama, members identify as ideologically closer to former Massachusetts governor Mitt Romney.

The same group gives a slight edge to a generic Republican in Congress over a generic Democrat.

Obama’s campaign argues that it’s a false contrast.

“Tax fairness and promoting opportunity go hand in hand,” said spokesman Ben LaBolt. “[T]he Buffett rule asks all Americans to do their fair share so that we can reduce the deficit, build an economy that lasts and restore economic security for the middle class.”

Yet a new Washington Post-ABC News poll found that on economic issues and job creation overall, they trust Obama and Romney equally. Romney outperforms Obama on the deficit.

But there’s more to the Buffett Rule story.

Fighty-eight percent of the same swing independents believe that the wealthy should pay more in taxes because “they aren’t paying their fair share.” Sixty-one percent think the wealthy should pay more because “they have benefited from our taxes and infrastructure.”

Democratic polling done after the State of the Union found swing voters “responded enthusiastically” to the Buffett Rule.

By hammering on the Buffett Rule, Democrats force Republicans to explain their opposition to higher taxes for millionaires.

Post-ABC News polling found that voters like Obama more than Romney, trust him more to protect the middle class and think he understands their economic problems better. The “empathy gap” is not to be taken lightly, and the Buffett Rule may already have helped Obama as much as it can.