An ailing Paul Simon stepped out of his retirement from show business Monday night to serenade delegates of the Democratic National Convention in Philadelphia with “A Bridge Over Troubled Water,” at once a plea for unity and a reminder of his own inability to get along with his one-time singing partner Art Garfunkel.

The song was the biggest hit for Simon and Garfunkel, but it was virtually the only song Simon’s curly-haired partner sang as lead. Over the years, the song has become like a child being tugged at in a custody fight. Garfunkel sings it to remind Simon he sang their biggest hit and Simon gives interviews in which he goes out of his way to compliment other singers’ versions.

A song that was supposed to symbolized unity and our obligations to take care of each other has come to mean something else–and when a sratchy Simon struggled through his rendition, it did not have the effect the convention planners were hoping for.

But, that was not all Simon‘s fault, considering what he walked into.

Simon was late coming to the stage, and Sen. Al Franken (D.-Minn.) and comedienne Sarah Silverman were asked to stretch out their act, which was not going as well as planned. Franken told the delegates that he was a Hillary Clinton supporter and Silverman countered that she was a supporter of Sen. Bernie Sanders (D.-Vt.).

“I’ve been hashtag ‘I’m With Her,'” said Franken.

“And this past year, I’ve been feeling the Bern,” said Silverman to cheers from the Sanders supporters. “Relax, I put some cream on it.”

Silverman, who wore a black dress with her black hair in a stout beehive, said that she will be proud of supporting Sanders.

“Bernie has succeeded in so many ways,” she said. “Not only did Bernie wake us up to what is possible and what we deserve.”

The star of the stand-up comedy film Sarah Silverman: Jesus Is Magic told the delegates: “Hillary heard the passion of the people–the people behind Bernie and put those passions into the party’s platform.

Clinton moved to unite the two campaigns, she said.

“I will proudly vote for her,” she said.

“It is just so inspiring, a few years ago she was a secretary and now she is going to be president,” said Silverman, who took out her wand for vaping marijuana at the 2015 Emmy Awards, saying that she was just going for a “a little puff-a-rooney.”

The point of the exercise was to demonstrate the power of Monday’s theme: “Stronger Together” and it was going well until Franken took his turn at the podium. Then, all the courtesy Sanders supporters gave to Silverman went away and the chants rose up: “Bernie! Bernie! Bernie!”

That was when the comedienne leaned over into the microphone and got real: “Can I just say to the ‘Bernie or Bust’ people? You’re being ridiculous.” Not good. First came the cheers from the Clinton supporters. But, as Franken tried to speak, the enraged Sanders supporters drowned him out: “Bernie! Bernie! Bernie!”

Franken said to Silverman: “Listen to that. This is what you did” and “This is the power of comedy.” But, the chanting did not stop. The Sanders supporters were standing and shaking the “Stronger with Unity” signs convention organizers had passed out, but Sanders supporters had copyedited with markers to read: “Stronger with Bernie.”

It was awkward and painful, as Franken babbled on, not wanting to do any more harm, and Silverman silently struck poses, mugging for the center field camera.

All the while, the Sanders supporters continued to chant.

Finally, Franken got word from off stage that the singer was ready and the two of them in relief announced: “Ladies and gentleman, Mr. Paul Simon.”