President Obama's grassroots campaign group has opened a campaign to belittle House Speaker John Boehner and GOP global warming critics, describing the climate change "deniers" as crazy, tin foil hat wearing believers in unicorns.

In three successive emails to supporters, Jim Messina, Obama's reelection campaign manager who now runs the president's Organizing for Action operation, portrayed Boehner and other Republican leaders as far out of step with the science of global warming, a harsh approach that is spoiling chances of a compromise on the issue.

One of Messina's emails opens this way: "Break out the tin foil hats, folks. House Speaker John Boehner and the chairman of the House Science Committee are both unsure whether the science behind climate change -- the stuff that shows pretty clearly that carbon pollution produced by humans is damaging our environment -- is real."

In another, he started, "If I said to you: 'Unicorns exist, I totally just saw one galloping down the street,' most likely you'd give me a sad look and get on with your day. But what if House Speaker Boehner and the chairman of the House Science Committee said they didn't know if the science behind climate change was real. Yeah. That actually happened."

It's all part of an effort to help Obama sell his program to reduce carbon emissions and deal with global warming, a key topic of his second Inaugural Address.

But the name calling campaign is rubbing Republicans the wrong way even as they grapple with differing views of the causes of climate change within their ranks. "The good cop-bad cop thing doesn't work. Cut the insults and let's get to work," said a key GOP leadership aide.