Here’s a brief history of President Trump’s record on pre-existing health conditions.

Did he pass the Affordable Care Act?

No. The president was not in Washington and not in politics when the Affordable Care Act was written, debated and passed in 2009 and 2010. The health law established consumer protections for Americans who buy their insurance, including a rule that health insurers must offer coverage to anyone who wishes to buy it, with prices varying only by region and the age of the customer.

Before Obamacare, some states protected people with pre-existing conditions in this way, but most did not. Americans with prior illnesses like cancer, asthma, even acne, often had trouble buying insurance for themselves and their families. One state that did protect people with pre-existing conditions was New York, where the media executive and presidential candidate Michael Bloomberg currently resides and where Mr. Trump did at the time. (Mr. Bloomberg’s recent television advertisements, which attack Mr. Trump’s health care record, appear to have prompted the tweets.)

The Affordable Care Act was a large and complex law, with many provisions that have proved controversial. But the protections for people with pre-existing conditions enjoy widespread public support.

Has he tried to weaken pre-existing conditions protections as president?

Yes. President Trump’s first legislative priority after his election was to “repeal and replace” the Affordable Care Act. Republicans in Congress voted on several different bills, but each of them had provisions that would have substantially eroded the current protections for Americans with prior health conditions, by weakening the regulations that make such insurance available, affordable and useful.

The bills would have weakened rules that require insurance to cover a standard set of health benefits, for example, and would have established policies that would have raised prices for people with a history of health problems.