The Edge performs with U2 in Philadelphia on June 13. (Owen Sweeney/Invision/AP)

Celeb: U2 guitarist the Edge (a.k.a. David Howell Evans), sporting a sleek black suit-no-tie combo and his signature stocking cap in a matching hue.

Cause: Evans has long been involved in promoting cancer research, particularly studies looking into the ability of certain foods to fight the disease. Prompted by his daughter’s leukemia diagnosis, he turned to doctors who were convinced that diet can affect angiogenesis, or the formation of blood vessels, a notion that some in the medical community call “unsettled science.”

Scene: Reporters caught up with the rocker, who said he’d had a day of productive meetings around the Hill, in the basement of the Capitol as he headed for Senate office buildings. That means he’s been working in Washington for three days straight — the band played the last two nights at Capital One Arena. The impromptu gaggle drew a few gawks from tourists and staffers passing by.

Sound bite: “It’s more difficult to find the common ground, but that makes common ground more important to find,” he told our colleague Paul Kane of the divisive mood in Washington. But in polished-lobbyist form, he noted that his cause is “a bipartisan issue.”