I'm sorry, I don't recall Obama not being President of the entire country, or pretending that he was only the President of those that supported him. I'm curious what specifically he did that makes you feel he didn't represent the entire country, other than implementing the political agenda he ran on?
Let me state up front, also, that I wasn't a huge fan of Obama. There were a lot of things I felt he should have done differently and really wish Romney would have beaten him in 2012.
What I recall is Republicans not supporting him, including the "not my President" line. Granted, it was largely stolen from Democrats talking about Bush (and possibly Republican's during Clinton), so that was nothing new. At the same time, you had National Republicans saying various things against Obama, like Mitch McConnell's saying the number 1 goal of Republicans was making Obama a one-term president. You had the Tea Party that seemed to be largely created to fight Obama's election (yes, I know, it was supposed to be about the deficit but it only gained momentum after Obama took office, despite the major recession funding programs Bush passed). And, of course, the Tea Party fell apart after Trump took office, replacing Obama, despite Trump increasing deficit spending.
I think your timeline of the Tea Party isn't quite right. The Tea Party started under the Bush administration. To be fair, you didn't claim it started before Obama, just that it "only gained momentum after Obama took office". But in terms of when it ended, it was on the decline before Trump. It's hard for me to remember things perfectly year by year, but by the time Trump was running for the Republican nomination, I don't think I had heard much of anything about the Tea Party for a good while.
Let's look, for example, at the Wikipedia article on the Tea Party from 2015:
Current status
Tea Party activities have declined since 2010.[146][147] According to Harvard professor Theda Skocpol, the number of Tea Party chapters across the country has slipped from about 1,000 to 600, but that this is still "a very good survival rate." Mostly, Tea Party organizations are said to have shifted away from national demonstrations to local issues.[146] A shift in the operational approach used by the Tea Party has also affected the movement's visibility, with chapters placing more emphasis on the mechanics of policy and getting candidates elected rather than staging public events.[148][149]
The Tea Party's involvement in the 2012 GOP presidential primaries was minimal, owing to divisions over whom to endorse as well as lack of enthusiasm for all the candidates.[147] Which is not to say the 2012 GOP ticket has not had an influence on the Tea Party: following the selection of Paul Ryan as Mitt Romney's vice-presidential running mate, the New York Times declared that the once fringe of the conservative coalition, Tea Party lawmakers are now "indisputably at the core of the modern Republican Party."[150]
So this mentions it was on the decline, and this was May 2015, before Trump had formally
announced his campaign. In fact, it's notable that even though this was 2015, it was unable to name much of anything they had done since 2012 (it goes on to mention a rally in 2014).
Notably, here's an article from several months before Trump's victory, let alone before he had did any increase in deficit spending:
So this was saying the Tea Party was dead, and before Trump won anything either. So it had fallen apart
before Trump was elected, not after (I suppose one could say it was in the process of falling apart before Trump was elected, and Trump simply finished it off--but make no mistake, it was of little relevance before Trump).
Come to think of it, Black Lives Matter seems to be going through a similar decline to the Tea Party. Both started out as loosely organized social movements, and then got a lot of attention and controversy. And then the Tea Party sort of faded away, and people stopped talking about or even particularly caring about it. Black Lives Matter seems to be suffering a similar fate; I'm not sure the last time I even heard the movement referred to outside of people talking about things it did in the past. Like the Tea Party, some of its
ideas continue onward, and have even been absorbed into one of the political parties; but the movement itself is of dramatically decreased relevance and I would not be surprised if, much like happened to the Tea Party movement's article, Wikipedia's article on Black Lives Matter opening words change from "Black Lives Matter (BLM) is..." to "Black Lives Matter (BLM) was..." at some point in the next five years.