They are the stadium giants of rock, one of the biggest draws in the business, who built a reputation on protest anthems and support for the global battle against poverty and Aids.
He is a powerful US Republican who, like every powerful US Republican with an election in the offing, needs to do a little fundraising. But Rick Santorum's plans to drum up cash on the sidelines of U2 gigs have not impressed the band.
"U2 concerts are categorically not fundraisers for any politician - they are rock concerts for U2 fans," said Jamie Drummond, executive director of DATA, an Africa advocacy group co-founded by U2 singer Bono.
With the band's Vertigo tour of the US well under way, the spokesman stressed that political fundraisers - a normal part of large music and sports events in the US - were in no way linked to the band, its music or its message.
"Neither DATA nor Bono are involved in these [fundraisers], and they cannot be controlled," he added.
Mr Santorum's get-together reportedly involves a $1,000 (£570) event during this weekend's Philadelphia show. Other events are planned for other shows on the tour, which runs until the end of December. And he is not alone. Hillary Clinton has also offered a small number of invitees the chance to join her in a suite in Washington at next week's gig. A cool $2,500 will secure the contributor a chance to rub shoulders with the Democratic elite while watching Bono and the Edge grind out the old favourites.
A spokeswoman for Ms Clinton said: "We do a meet-and-greet with the senator, and then go in and listen to music."
Mr Santorum's press secretary, Robert Traynham, said yesterday that the Pennsylvania senator's decision to hold a fundraiser during Sunday's Philadelphia show is based on his "deep respect and admiration for Bono and their work together over the last few years to fight the global spread of HIV-Aids."
Mr Traynham said Mr Santorum's office has not spoken with Bono about the issue, but that it is routine for elected officials to host such fundraisers at sporting and cultural events.
The fundraiser will go ahead as planned, Mr Traynham said.
