And survival will be a real issue. The bottom line of the G.O.P. approach is that millions of Americans will lose insurance, and thousands more will die unnecessarily each year because of lack of care.

The paradox of Obamacare is that it is both unpopular and saves lives. Preliminary research suggests that it has already begun saving lives, but it’s too early to have robust data on the improvements to life expectancy among the additional 20 million people who have gained insurance. It is notable that an Urban Institute study found that on the eve of Obamacare’s start, lack of health insurance was killing one American every 24 minutes.

One careful study found that the Republican health care plan in Massachusetts, which was the model for Obamacare, noticeably lowered mortality rates. For every additional 830 adults covered by insurance, one death was prevented each year.

The American College of Physicians warned this week that the G.O.P. course could result in seven million Americans losing their health insurance this year alone, by causing parts of the insurance market to implode. Back-of-envelope calculations suggest that the upshot would be an additional 8,400 Americans dying annually.

How can insurance make such a difference?

I’ve written about my college roommate Scott Androes, a fellow farm boy from Oregon, who switched careers in 2003 and didn’t buy health insurance on the individual market because it was so expensive. Then in 2011 he had trouble urinating and didn’t see a doctor because of the cost.