If you wondered why unions worked so hard to help President Obama push for his 2010 federal health care reform law — when so many union members already enjoyed the fruits of generous health insurance plans — Mallory Factor offers some thoughts in both a new book and the latest issue of Forbes.

The real reason unions fell behind ObamaCare is that the law throws the door wide open for unionizing most of a 21-million-member health care workforce. Right now only about one and a half million of America’s health care workers are unionized, less than 10% of the total. Many are self-employed or work in small offices and can’t be unionized under current law. But the unions have several plans to overcome this hurdle, with the ultimate goal of unionizing every health care worker in America.

The first plan is to drive more doctors, nurses and other health care workers to fold their private practices into large hospitals. Once employed by hospitals, health care workers can be unionized as private hospital workers or as government employees if they work for government hospitals. This plan is working great for the unions — by next year, for example, only 33% of doctors will be in private practice, down from 57% in 2000.

One suspects the prospect of a large spike in union membership sends a chill up George Leef‘s spine.