The middle class in America have it made, and yet protectionists whine at the lack of "good manufacturing jobs", as if manufacturing does not need to increase per worker efficiency (i.e. make more with less). Look around, anyone with the drive to succeed, barring geographically work shortages, can become middle class in today's America.
Of course, middle class is not a defined term and the demagogues will just redefine middle class to suit their own agendas, instead of predefining the middle class and playing fair.
And a BIG yes, to your last statements about not defining what constitutes the middle class. The middle class is now and always has been comprised of three parts; the lower, middle and upper strata of what is generally called the MIDDLE CLASS. The latter group is comprised of quite wealthy people; however, they are still middle class!