Mr. Trump and his defenders are increasingly taking the position that what he did in pressuring the Ukrainian president was no big deal — the responsible course of action, even. Ergo, the more governments that Mr. Trump urges to do the same thing, the more normal, if not public-spirited, such aberrant presidential behavior will seem. The cynical marketing calculation — Mr. Trump’s favorite form of math — would seem to be that, as with previous administration outrages, the news media will grow weary, the public will grow numb, the Democratic inquisitors will appear ineffectual. Mr. Trump is also, of course, seeking to drag former Vice President Joe Biden and his son, Hunter, down to his level and implicate them in the same kind of self-dealing that he and his own family stand accused of.

This might work. But it also might not. There is no historical precedent for a president demanding that a foreign government investigate another American politician. If Mr. Trump has evidence of possible corruption overseas, his counsel should relay it to the Department of Justice and let the F.B.I. do its job, in coordination with its foreign counterparts.

Instead, Mr. Trump used his telephone conversation with Mr. Zelensky to pressure him to do Mr. Trump a “favor” and consult with Rudy Giuliani, serving as Mr. Trump’s personal lawyer and unofficial envoy, and the attorney general, William Barr, about digging up dirt on the Bidens. At that time, the United States, under direct orders from the president, was withholding nearly $400 million in military aid appropriated by Congress to help Ukraine defend itself against Russian encroachment on its eastern border.

Much remains unknown about how the various dots do or do not connect. But basic facts of the Ukraine approach are not in dispute. Nor can there be much question about what Mr. Trump so publicly asked China to do.

There is a certain twisted logic to the president’s approach.

M ultiple Republican lawmakers have stepped forward to declare the July 25 phone call, as Senator Lindsey Graham of South Carolina put it, “a nothing (non-quid pro quo) burger.”