During a House hearing on climate change last week, Massachusetts congressman Ed Markey reportedly read from a letter written in 2003 by Mitt Romney, then the Bay State’s governor, to the governor of New York. In it, Romney expressed support for a regional cap-and-trade program then in development and bragged about his state’s efforts to curb emissions. Markey argued Romney’s views nine years ago qualified him as cap-and-trade “visionary.”

Markey’s words may be easy to view as part of a joke. But they’re not. One of the barest truths about this country’s energy and climate debate is that just like in its healthcare debate Democrats are pushing ideas once supported by the GOP, while Republicans are running away from said support as fast as they can. Writing for the New Yorker, Ezra Klein does a great job explaining how this has worked out in the context of the healthcare debate. Along the way he points out that only five years ago both John McCain and Newt Gingrich wanted a cap-and-trade system to reduce carbon dioxide emissions.

The question is: how many folks belonging to the seemingly shrinking (and at least relatively silent) pool of independent voters notice this such flip-floppery? And do they care?