A major donor to Mayor Bill de Blasio pleaded guilty to using campaign contributions as bribes to buy better treatment at City Hall — and yet the mayor, who took the money and aided the donor, was not charged with a crime.

Another donor pleaded guilty to honest services wire fraud that included making political contributions in exchange of official action — and again, no charges for the mayor.

The outcome has led some, including the WNYC radio host Brian Lehrer, to an obvious question.

“How can someone be guilty of giving you a bribe and you not be guilty of taking it?” Mr. Lehrer asked Mr. de Blasio on Friday.

“It’s abundantly clear,” the mayor said. But it wasn’t.

“This man did a lot of bad things in a lot of places,” Mr. de Blasio said of Harendra Singh, a restaurateur who pleaded guilty to bribing the mayor. “I’m someone who never did, never would be involved in such an effort.”