Yet several years ago, when Gemignani's son, Alexander, showed up to try out for a new production of Assassins, composer/lyricist Sondheim was taken unawares.

"I had no idea Alexander had any aspirations whatsoever to becoming either an actor or a singer," Sondheim says. "It was a complete surprise to me when he first came in to audition, and an even greater surprise that he was so accomplished in both fields."

At that time, in fall 2001, Assassins was preparing to make its Broadway debut, produced by the non-profit Roundabout Theatre Company. Then the attacks of Sept. 11 occurred, and suddenly the prospect of staging a musical focusing on real-life murderers and would-be murderers of American presidents — from John Wilkes Booth to John Hinckley Jr., the role that Alexander won — made some people uneasy. The show was postponed indefinitely, but the cast and creative team, including both Gemignanis, gathered for an emotional final reading that December.

"It was bittersweet," recalls Paul, 60, sitting with Alexander, 24, in a midtown rehearsal hall. "A producer stood up and said, 'You know, we are going to do this. We're committed to it.' "

Indeed, the Roundabout's Assassins, now in previews, will finally open at Broadway's Studio 54 on April 22, with most of the 2001 lineup still in tow. (Only three original cast members — John Dossett, Raul Esparza and Douglas Sills — had to bow out, owing to other commitments.) It marks only the second time that the Gemignanis have worked together professionally, the first being a workshop of Sondheim's 1974 play The Frogs, which Lincoln Center will present in an expanded version starring Nathan Lane this summer.

Yet Paul clearly has admired his only child's gifts — which also include playing trumpet, piano and guitar — for many years.

"He's an extraordinary musician, but he decided that his real love was acting," the proud dad says. "He could do anything he wants to do. He won't say that, but I will, and not just because I'm his father. I wish I were half as talented as he is."

Alexander's mother, Carolann Page, also is an accomplished singer and actor. And while growing up in Tenafly, N.J., the younger Gemignani sometimes accompanied his dad to work, sitting backstage or in the pit as the musicians and actors ran through their paces. But his parents did not push Alexander to follow in their footsteps. "My folks never said, 'You must pursue a creative field.' I just was always interested in music. I guess the only other thing I was interested in was baseball."

The role of Hinckley poses a heftier dramatic challenge than the fledgling performer's previous outings, which include regional productions of such classic musical comedies as Bells Are Ringing and Oliver!, as well as the off-Broadway incarnation of the satiric hit Avenue Q.

For Alexander, this Assassins, which examines larger social and cultural conditions that surround and influence its subjects, also is especially timely: "I think it's important that we do this show now, and that people see it."

Paul concurs. "Some people look at this show on the surface and say, 'You're deifying killers.' But they haven't thought about it long enough, or deeply enough. If anything, it seems more current now than when we first started doing it. There is more of a Big-Brother-watching-you atmosphere than we've had before, and everyone has become more politically conscious because of the cowboy in the White House.

"Doing this show is like getting a date with your favorite cheerleader," Paul says. "Finally, after getting pushed aside two or three times, you get to go ahead with it — and at the best possible time, with an extraordinary cast and director. Maybe somebody's controlling this thing and we just don't know about it."