Just over a month ago, it was falsely claimed that Sarah Palin had been a member of the Independence Party during the 1990s. Media outlets jumped on that false claim and reported it as fact. The New York Times, to take just one example, printed the report and subsequently had to run a correction.
There is now strong evidence that during the 1990s, Barack Obama was a member of the socialist New Party, an arm of the Democratic Socialist Party of America. So far, to my knowledge not a single "mainstream" news outlet has followed up on this report, let alone immediately report it as fact, as they did with Sarah Palin.
Why do you suppose that is?
I suspect it's because the media is going to see the Obamessiah elected or die trying.