Long before anyone purchased a plan on Healthcare.gov, President Barack Obama repeatedly promised the hundred-plus million people in the country who were already insured— through their employers, or public systems like Medicare and Medicaid—that their coverage wasn’t at risk. “If you like your plan,” he said often, “you can keep your plan.” That infamous guarantee became a powerful weapon in Republicans’ anti-Obamacare arsenal when Americans began receiving cancelation notices from their insurance companies ahead of the law’s 2013 rollout.

Obama’s mantra wasn’t devised to be devious; it was a rhetorical flourish meant to convey in simple terms just how incremental the Affordable Care Act would be. Rather than overhaul the entire health finance system, the law would leave the vast majority of existing arrangements undisturbed, while fixing the dysfunctional individual market for everyone else. “You can keep your plan” was far closer to the truth of the matter than the GOP’s depiction of the ACA as a socialist takeover of the health care system, but Republicans, being fully out of power, weren’t the ones making policy.

Nobody was obligated to interpret Obama’s comments generously, and to this day many people do not. He made a categorical statement that, categorically speaking, wasn’t true. But it is remarkable, thinking back on it, just how damaging that talking point turned out to be. Obamacare creates far more winners than losers; the universe of people whose individual market plans were canceled three years ago is much smaller than the number of people who became newly insured thanks to the law.

Still, the stark contrast between the words “you can keep your plan” and thousands of unexpected cancellation letters made for toxic politics.

It’s been said, and not just by liberals, that President Donald Trump and congressional Republicans are repeating this error with their own promises about the GOP health care plan. Months ago, the conservative health care writer Phil Klein warned Republicans that they were “falling into the same trap that Obama did.”