WASHINGTON — Over four decades in public life, President Trump has sought to bend business, real-estate and political rivals to his will. Facts that cut against his position have been declared false. Witnesses who have questioned his motives have been declared dishonest. Critics of his behavior are part of a corrupt, shadowy effort aiming to damage him.

And, as he likes to put it, his own actions are always, to one degree or another, “perfect.”

That approach — which proved effective when Mr. Trump faced off against the special counsel, Robert S. Mueller III — is about to face a formidable test as the impeachment process moves forward.

The White House and congressional Republicans allied with Mr. Trump are preparing for a Senate trial in which they will not only declare Mr. Trump’s innocence but also present a version of events that portray him as the victim of a broad plot to undermine his presidency even before it began.

That narrative will include claims that Ukrainians meddled in the 2016 election instead of the Russians — an unfounded allegation refuted by the administration’s own intelligence agencies as recently as this week — and that Hunter Biden, the younger son of Vice President Joseph R. Biden Jr., used his father’s connections to make money in Ukraine.