Freeing companies from a U.S. government mandate to offer employees health care is setting off a chain of events that may enlarge the pool of uninsured Americans. That may be good for President Barack Obama's health-care overhaul.

The success of the 2010 Affordable Care Act is largely dependent on how many people are willing to buy subsidized health plans through government exchanges. Most of the people affected by Obama's decision this month to delay the employer mandate to provide health care will now be eligible to use the exchanges when they open Oct. 1.

The law's creation of state-by-state marketplaces had targeted about 26 million of the more than 50 million uninsured Americans for coverage. “A few million” more may now be made eligible by the delay, said Larry Levitt, senior vice president at the nonprofit Kaiser Family Foundation research group.