Jay Cost makes a pretty strong case that it is.  The Republicans started pulling into parity with Democrats after the disastrous town hall meetings of August 2009, and the Democrats plummet around the turn of the year, when health care was the main focus of political coverage.

Earnest question:  which national policies in history have started unpopular, passed, and then gotten much more popular?  I'm not talking about things that started popular and then developed vehemently entrenched constituencies, but rather, things that started unpopular, and then people eventually realized they liked them.