But his perception among voters and the party establishment isn’t the only thing getting hit. Now, despite his tendency to use controversial statements to his advantage, “the Trump brand had been negatively affected” by the tape, according to a Brand Keys poll of 1,536 registered voters across the country.

Before Mr. Trump entered the race, adding the Trump name to virtually any product or service increased its perceived value, according to Brand Keys.

In 2015, that “added value” was anywhere from 20% to 37%, depending on the category, said Robert Passikoff, Brand Keys founder and president, in a statement. “That’s a range enviable by any category or brand standards,” he said.

As of June 2016, when Mr. Trump was already the presumptive Republican nominee for president, the added value of the Trump brand in entertainment was as high as 43%.