Don’t blame the health law for high levels of part-time employment. In fact, using the law’s definitions, part-time work isn’t increasing at all as a share of employment, at least not yet.

Nearly 8 million American were working part-time in September because they couldn’t find full-time work. Overall, 27 million people — nearly a fifth of all employees — are working part-time, well above historical norms.

Many critics of the Obama administration have pointed the finger for the prevalence of part-time jobs at the Affordable Care Act, the 2010 law better known to some as “Obamacare.” The law’s so-called “employer mandate” requires most midsize and larger companies to offer health insurance to their full-time employees. That, critics argue, provides companies with an incentive to hire part-timers instead.

The Obama administration earlier this year said it would delay the requirement until 2015 to give companies more time to comply. But some employers have said they are nonetheless cutting back on full-time hiring. Indeed, part-time employment rose early this year, while full-time employment growth stalled.