It was a crowded field this year, but PolitiFact has named their Lie of the Year:
In the spring of 2009, a Republican strategist settled on a brilliant and powerful attack line for President Barack Obama's ambitious plan to overhaul America's health insurance system. Frank Luntz, a consultant famous for his phraseology, urged GOP leaders to call it a "government takeover." [...]
PolitiFact editors and reporters have chosen "government takeover of health care" as the 2010 Lie of the Year. Uttered by dozens of politicians and pundits, it played an important role in shaping public opinion about the health care plan and was a significant factor in the Democrats' shellacking in the November elections.
So kudos to the Republican Party for successfully parlaying a blatant lie into significant electoral gains last month. But of course they can't take all of the credit:
But as Republicans smelled serious opportunity in the midterm elections, they didn't let facts get in the way of a great punchline. And few in the press challenged their frequent assertion that under Obama, the government was going to take over the health care industry.
But don't be too hard on the traditional media ... after all, Sarah Palin tweeted it so it must have been true.