Early in the summer, the state led the nation in new infections per capita. It hit a peak of 4,797 new cases one day in late June, but new infections declined after Gov. Doug Ducey, a Republican, reversed himself and allowed local governments to require residents to wear masks.
While Mr. Trump is trying to recreate certain conditions of the 2016 campaign, he has not achieved his own level of relative discipline in the final two weeks that year. Back then, he tempered some of his incendiary comments and tweets.
His performance so far this week does not suggest that is in the offing.
In Arizona, he bounced from joking about the perils for a president of engaging with corporate officials while seeking donations to airing a litany of grievances against people including former President Barack Obama and Michelle Obama, the Bidens, Dr. Fauci again, and two female NBC News hosts, one of whom recently interviewed him and the other of whom is set to moderate the final debate.
He also praised himself for straying from the prepared speech on his teleprompter.
Earlier, the president’s campaign manager, Bill Stepien, announced the advertising spending on a call with reporters. The $55 million spending plan comes as some senior campaign advisers have described a cash crunch affecting the kinds of so-called hard-dollar donations that pay for advertising.
The ads will be funded by the campaign and the Republican National Committee, and will focus mostly on the Sun Belt and the Rust Belt, including Arizona, Iowa, Ohio, Michigan, North Carolina, Florida, Pennsylvania, Georgia, Nevada and Wisconsin.
The Trump campaign has been out-advertised on the television airwaves for weeks, but Mr. Stepien praised the ground operation built by the R.N.C. as a countervailing force.
And he said that Mr. Biden’s late push on the ground to pull voters to the polls and to sway undecided voters was simply “too late,” and that early voting numbers were not as favorable to Democrats as they seemed to be.