By Jennifer Rubin

President Donald Trump promised a magnificent health care system that cost less, gave more choices and provided better care. Such a plan never existed.

In the less-than-exacting mainstream coverage of his campaign, he escaped scrutiny in a way Hillary Clinton or Sen. Bernie Sanders, I-Vt., did not on their health care proposals. That was a failure of the media but also a campaign lesson for candidates: If you are going to be specific about very, very ambitious proposals, you better be able to explain how you enact them.

We have seen this play out in the preliminary skirmishes in the Democratic presidential race on Medicare-for-all and on the Green New Deal. As to the latter, the GND is a resolution (i.e., a wish list) that declares it the “duty” of the federal government in 10 years to, among other things, achieve “net-zero greenhouse emissions,” ensuring that any infrastructure bill considered by Congress address climate change and “meeting 100 percent of the power demand in the United States through clean, renewable and zero-emission energy sources.”

It also throws in a grab bag of “guarantees” for housing, union jobs and “justice and equity by stopping current, preventing future and repairing historic oppression of indigenous peoples, communities of color, migrant communities, deindustrialized communities, depopulated rural communities, the poor, low-income workers, women, the elderly, the unhoused, people with disabilities and youth.”

How we obtain, define, pay for and pass all of those things remains unexplained. Its sponsors want to avoid answering all the hard questions and simultaneously maintain the pretense that they have a concrete plan. Instead, they wind up being criticized for a plan that costs — dream up a big number — and that can be obtained only through a command-and-control economy that most Americans abhor. Saying you support the GND, then, means what precisely?

One interpretation is that, sure, you’d insist we spend trillions and turn the economy inside out. You’d push for this or nothing even though such a plan is out of the realm of possibility. Well, if you don’t dream big, you don’t get it! If that’s the meaning behind “signing on to the GND,” then progressives are in for a heap of well-deserved criticism and the Democrats risk losing the opportunity to oust Trump. The voters are asked to choose between climate change denial and climate change fantasy.

Another interpretation of “sign on to the GND” is that you simply endorse the GND’s general goals. You’re giving thumbs up to what House Speaker Nancy Pelosi, D-Calif., called the “Green New Dream — or whatever they call it.” That’s like saying you want to cure cancer by the end of the century. It’s not meant to be taken literally; it’s inspirational, like world peace.

The problem, however, is that once you say you “support the GND,” you are stuck defending the text of the GND. (And by the way, there is considerable confusion about what is actually in the GND).

Turning very ambitious goals into precise mandates is fraught with political peril and altogether unnecessary. Take away the 10-year mandate and set out reasonable goals, for example, to “reduce greenhouse emissions by X percent.” Then you can lay out some concrete ways to get there.

Jennifer Rubin writes for The Washington Post.