Mr. Trump’s ratings are poor for an incoming president, no matter how you cut it. The question is whether his ratings are merely poor or disastrous. If his approval rating were taken at face value, there would be an argument that his presidency could be in jeopardy before it even started.

In general, the postelection period is about as good as it gets for an incoming president. But recent surveys put Mr. Trump’s approval rating around 40 percent — as bad or even worse than President Obama’s approval ratings heading into the 2010 and 2014 midterm elections, when Democrats were dealt huge losses.

Mr. Trump, to some extent, has incurred expected and inevitable losses in advance of his presidency. Years of controversial remarks have given him the political baggage that typical presidents of this era, like Mr. Obama, inevitably pick up over their first two years.

But Mr. Trump’s ratings aren’t just below those of past incoming presidents; they’re also below re-elected presidents like Mr. Obama and George W. Bush. The postelection honeymoon phase lifted Mr. Obama and Mr. Bush’s approval ratings well over 50 percent after their re-elections, despite all of the scars of their first terms.

Some of Mr. Trump’s polling weakness can also be attributed to the difference between adults and likely voters. The adult population is much younger, more diverse and likelier to have been born outside the United States than the voting electorate. Most of the recent polls have measured Mr. Trump’s ratings among all American adults, not registered or likely voters.