As I said, politics are ugly, always have been, and surely always will be, but there was, in fact, a period of bipartisanship in American politics that no longer exists. Compared to the present, Reagan enjoyed considerable bipartisan support. But I dispute your characterization of the Tea Party. It may be more precisely libertarian in origin, but it's evolution is now inextricably linked with the Republican party.
I make no attempt to excuse Obama policies that failed, or his decision to bail out Wall Street rather than Main Street in the aftermath of the housing market crash. I'm not really sure with what this has to do with the original question of divisiveness. But since you're gonna throw shade at Obama, let's be fair about our current president, who claimed to speak for the working man in the forgotten corners of America, but has completely abandoned these people in favor of billionaires and corporate America. Small businesses are being destroyed during covid, and small farms ravaged in the trade war with China. The problem with the conservatives on this board is they're so busy trying to defend the president that they don't hold him accountable for anything. The extreme right blames the left for killing small businesses because of shutdowns, but Republicans, including Trump, could choose to funnel aid to small businesses, instead the money specifically set aside for Average Joe is going to the wealthy.