WASHINGTON — On a former trading floor in an office tower in Rosslyn, Va., with sweeping views of the Potomac River, the Trump 2020 campaign is settling in. It has about 40 staff members and counting, reported $19.2 million in cash on hand in its last report and has spent $4.5 million on online ads since December.

It is a long way from Mr. Trump’s first presidential race, which came together in the summer of 2015 and was run as a taped-together operation, with a few desks strewn across an unfinished floor of Trump Tower.

But one thing is missing from the high-powered but traditional campaign operation underway in Rosslyn: a candidate who abides by tradition.

In a speech to a conservative group this month, as Mr. Trump described what he had in mind, he made a point of recounting “how I got elected, by being off script,” adding, “If we don’t go off script, our country is in big trouble, folks.” And at a rally in Grand Rapids, Mich., on Thursday, Mr. Trump illustrated what he meant, delivering an 80-minute stemwinder in which he lashed out at familiar targets who fostered “the collusion delusion” and offered the in-depth rehash of his 2016 victory that is a staple of his rally speeches.