Bono has been attacked by his rock peers for associating with US President George W Bush and British Prime Minister Tony Blair.
The U2 rocker recently admitted friction has been sparked within the band since his transformation from rock star to anti-poverty campaigner.
But fellow musicians are concerned Bono is taking his desire to make a global difference too far.
Fellow Irish star Sinead O'Connor says: "I think you risk losing your credibility by going to a party at Downing Street.
"I would draw a line at drinking wine and eating cheese with the Prime Minister."
Meanwhile, songwriter Billy Bragg says: "Bono is prepared to sit down and talk directly with George Bush in his territory.
"He has put his credibility on the line."
But U2 guitarist The Edge is tight-lipped about tensions within the Vertigo group.
He says: "I think he's doing a fantastic job but I do not have the time. I am too busy in the studio recording."