NEW YORK (CBSNewYork)Mayor Bill de Blasio faces a new political hurdle.

Stunning testimony from one of his major donors claims the mayor gave the green light for illegal campaign donations.

They say a picture is worth a thousand words, but the pictures entered as evidence in a Long Island corruption trial are likely to cause de Blasio a thousand political headaches — photos showing him alongside Queens restaurateur Harendra Singh.

“It has got to affect his image and also his power,” said Profesor Doug Muzzio of Baruch College.

Singh, who raised thousands for de Blasio and threw free fundraisers, testified under oath that when he told de Blasio he would have to arrange illegal campaign donations his response was “Do what you got to do, but I don’t want to know.”

Singh is testifying as a prosecution witness in the corruption trial of former Nassau County Executive Edward Mangano. Singh has pleaded guilty to bribery charges of both Mangano and de Blasio and said he raised funds for de Blasio to get favorable treatment on a lease dispute for his Long Island City restaurant Water’s Edge.

Asked if his contributions to de Blasio were bribes, Singh said “Yes, in exchange of help, you know, at Water’s Edge, getting the lease extended.”

“Its sounds like a scene from ‘The Sopranos.’  They’re in the diner and they’re colluding about a deal,” Muzzio said.

Singh’s testimony – and the front page headlines it brought – couldn’t come at a worse moment for de Blasio, who is seeking to build his national clout as the champion of progressive issues, Kramer reported.

De Blasio has to deal with a newly emboldened City Council, and there’s his protege Cynthia Nixon, who wants to unseat “frenemy” Andrew Cuomo.

“Not the best day Mayor de Blasio ever had,” said political consultant Hank Sheinkopf. “He should somehow figure out how to get Mr. Singh to shut up quickly, because every time Mr. Singh opens his mouth, de Blasio feels more pain.”

What could be even more damaging is if the mayor is called as a witness in the trial. Defense attorneys say they’re making up their minds about that.