Monday was supposed to be the final day to sign up for health insurance under the Affordable Care Act, but as with all things in Obamacare, it is a flexible deadline—which explains both the program's momentum and why it is still vulnerable and unpopular.

The numbers say Obamacare is a success in New York. Figures released by the state Department of Health a week ago show

that 717,000 people have signed up for coverage under the state's exchange. Just over half qualified for Medicaid. Some 344,000 picked private insurance plans, a 60% increase in three weeks. Updates to be announced this week likely will be even more impressive.

Increasingly, the program is achieving its primary aim of boosting the number of people with health insurance. Seventy percent of the New York enrollees were previously uninsured, the department said, which means a 20% reduction in the 2.2 million New Yorkers without coverage.