My longtime working definition of an American political "independent" is a Republican who is too lazy to volunteer to campaign for their favorite GOP candidate and too cheap to donate to their favorite GOP candidate.
Over the years I've added the addendum that, by and large, these same so-called "independents" are suburban, white and professional, or coordinator, middle class, i.e. mid-level corporate managers, doctors, lawyers, small business owners, insurance agents and so on. In short the base of the Glenn Beck "teabagger" movement.
They are motivated by greed. Even though the majority are comfortable economically and have incomes which puts them in the alternative minimum tax, AMT, bracket, they always want more. These are the folks who are always whining at the "tea parties," that "we know how to spend our money better than the government."
And they are motivated by envy. Curiously they envy and begrudge the poorest segments of society. Envious in that "independents" envision the poor living the life of Reilly on food stamps and welfare and begrudging ever one of their tax dollars they imagine going to support that imagined lifestyle.
What American "independents" secretly and really want is to live on The Big Rock Candy Mountain, paying no tax yet still receiving all the services and benefits only government can provide.
To that I add that the reason why establishment Democratic politicians and liberal commentators are blind to the economic class element of Glenn Beck-Ayn Rand acolytes is because they are of the same socio-economic class: white, suburban, professional or coordinator class with a commensurate income and social status. And while not as odious as their fellow Beck-Randites, having a social conscience, they do everything to preserve their social status and income, i.e. tax incentives, deductions, credits etc. Establishment Democrats/liberals too want to continue living on The Big Rock Candy Mountain.