Everybody falls into one or even more than one protected class. That is, everybody except white males. We're hiring tiny women. Size is no longer a criterion for firefighters. Such resentment naturally translates into a heightened sexism.
Affirmative action is fertile ground for the evil it ostensibly opposes.
Perhaps this is inevitable for a policy that enshrines its own version of sexism into the legal system. Allocating jobs via a quota system rather than merit has disastrous long-term economic consequences. And it drives a wedge between individual worth and economic success. The second common justification for affirmative action is the argument from compensatory justice. This claims that anyone who injures an innocent person should compensate the injured party for the damage.