It was enough to talk about socialism and having a bigger governmental role, and people (on both parties) seemed to start distancing themselves from Obama.
If he doesn't succeed, I am not sure there will really be another chance in time to make a real difference (i.e. to keep USA as no.1... I have no doubt USA will continue being a rich country for a long time to come).
I think foreign observers think that the American public is atavistically motivated by invocations of "socialism" because they view the US through the lens of their own politics. In reality, Obama is unpopular because the economy is in the shitter and unemployment is running near 10%. It doesn't matter whether that's fair or not.
My impression of cause and effect was that it started pretty much from the beginning, when Obama tried to push for economic stimulus first and universal health service later.
And now the teaparty are a force to be reckoned... and their whole point is to have a small government, and they don't want stimuli or similar (as well as no health service).
But please tell me more. American politics is quite interesting. :)