Paul Ryan‘s closing statement included a claim that 20 million people are projected to lose their employer-sponsored health insurance once the Obama health law takes effect.

That comes from a possible scenario mentioned deep into this March 2012 set of estimates by the non-partisan Congressional Budget Office that contemplates what employers might do after 2014 when many will be penalized for not providing insurance but can also look to new options such as subsidies towards the cost of premiums for private insurance or Medicaid coverage for low-income workers.

But it’s far from certain what will happen, and 20 million fewer people in employer-sponsored insurance is the most extreme number considered by CBO in its study. More likely, it thought, was that 3 to 5 million fewer people might get insurance through their employer each year from 2019 to 2022, and would instead get their insurance through exchanges, with the subsidies, or Medicaid.