The experience of Mitt Romney’s Massachusetts, O’Brien concluded, shows how this works: enrollment in Romneycare spiked when the mandate kicked in, and it spiked for healthy people — presumably because they accepted the “positive responsibility” of the mandate, and bought health insurance because it’s what they were “supposed to do.”

But this example does not necessarily bode well for Obamacare’s unfolding. The Massachusetts law was a bipartisan bill passed in a wealthy, homogeneous state with a pervasive left-liberal ethos. The national health care law aspires to create the same sense of “positive responsibility” in a much more polarized, fragmented, socioeconomically diverse and libertarian-minded society, roughly half of which opposes the law outright.

This was always going to be a lift even without technological problems and “if you like your plan, you can keep your plan” disillusionment. Now it’s much, much heavier.

Consider the findings of a new poll from Harvard’s Institute of Politics. Among the traditionally pro-Obama millennial generation, the core group that the White House needs to “follow the rules” and buy a policy, the president’s approval ratings have dropped to 41 percent, and support for Obamacare has also plunged: 56 percent of 18- to 29-year-olds disapprove of the law, a majority say it will increase costs, and just 18 percent say it will improve their care. Meanwhile, a new National Journal survey finds that a majority of millennials expect the law to be repealed outright.