But the deeper force at work, the reason that these near-death experiences keep happening, isn’t a website or a broken presidential promise. It’s a problem inherent to contemporary liberalism, which is that liberals’ proudest achievement, the modern welfare state, tends to resist, corrupt and baffle their efforts at comprehensive reform.

This was the message of Jonathan Rauch’s book “Government’s End,” which was first published in the Clinton era, and which I’ve recommended before as essential to understanding liberalism’s struggles in the Obama years. Because our government spends and regulates so much, Rauch argued, because its influence sprawls into so many walks of life, because so many clients and beneficiaries and interest groups depend on its programs and policies, the policy status quo is far harder to dislodge today than it was during the Progressive Era or the New Deal or the Great Society.

This status quo bias is structural rather than ideological; it frustrates limited-government conservatives as well as liberal technocrats. But the frustration has been much more acute and ironic for Democrats, who find themselves handcuffed by the very achievements they aspire to emulate, and attacked by the beneficiaries of yesterday’s liberal programs when they attempt to propose programs for tomorrow.