But with less than eight weeks left until the election, and with early voting beginning in some states this month, the number of days Mr. Trump can afford to burn is dwindling. He is trailing his Democratic rival, Joseph R. Biden Jr., in most national and battleground state polls, and is facing a potential cash crunch, leaving him with less to invest in television ads after aggressive spending over the last three years.

Nevertheless, Mr. Trump has spent the last week playing defense, first in the wake of a report that he referred to Americans who died in combat as “suckers” and “losers,” and then doing damage control after the release of excerpts from the veteran journalist Bob Woodward’s new book, “Rage.”

“Even though the calendar says 54 days, it’s really more like 40 days,” Mike Murphy, a veteran Republican strategist and former adviser to Jeb Bush, said Thursday, with a nod to the early voting. “And so every day, Trump is burning the one thing he can’t create more of, which is time — which is a disaster for him.”