The White House says Obamacare isn't a job killer. But what if it's not killing jobs so much as pushing workers into part-time employment? Jed Graham at Investors Business Daily points to some data in the Current Population Survey which suggests that's exactly what's going on:

Even as the number of people working has grown by 2.2 million, or 1.6%, over the past year, the number clocking 30 to 34 hours a week has shrunk. In the second quarter, the number of workers putting in 30 to 34 hours at their primary job fell by a monthly average of 146,500, or 1.4%, from a year earlier. By comparison, the number working 25-29 hours per week in their primary job rose by 119,000, or 2.7%. This oddity has an obvious explanation: ObamaCare's employer mandate applies only to full-time workers, which the law defines as 30 hours per week.

What appears to be happening, in other words, is a threshold effect. People hovering around the borderline—just above 30 hours—are seeing their hours capped. And new positions that might have offered 32 or 34 hours of work in the past are being created as 25-29 hour a week jobs.

Some additional anecdotal evidence that the law is making it harder for workers to get more hours on the job comes from Greg Mankiw's blog. Mankiw, the chairman of the Harvard economics department, posted a letter from a college instructor today reporting that part time faculty are seeing their hours capped in order to avoid the law's penalties for not offering insurance coverage. An excerpt:

With the implementation of the ACA (Affordable Care Act) these institutions are giving notification to their part-time faulty that their individual teaching schedules will now be limited to three sections. At the college this will likely result in the cancellation of 20-25% of the class sections in economics, and I would assume other areas will have a similar result. The students are not fully aware of the situation and many will be surprised that their desire to get a college education is now being impacted by the need to avoid the full implementation of the ACA.

The part-time push may even be affecting people working directly to implement the law. As the J.D. Tuccille noted last week, one of California's Obamacare call centers reportedly indicated it would provide employees full-time jobs with benefits—and then decided that half the jobs would be part time, with no health benefits.