Martin Sheen and others from the cast of The West Wing, the TV drama about a liberal president and his staff, were invited by first lady Jill Biden for an event to mark the 25th anniversary of the show.
Sheen exhorted the crowd to find something worth fighting for, "something deeply personal and uncompromising, something that can unite the will of the spirit with the work of the flesh".
His voice and hands rose, his cadence matching perfectly that of President Jed Bartlet, the character Sheen played for seven seasons.
"When we find that, we will discover fire for the second time, and then we will be able to help lift up this nation and all its people to that place where the heart is without fear, and their head is held high," Sheen said.
The West Wing remains a favourite of many who now work in Washington, both liberal and conservative.
Martin Sheen, who played President Jed Bartlet, exhorted people to find a cause worth fighting for. (AP PHOTO)
Among those spotted in the Rose Garden were House Foreign Affairs chairman Michael McCaul, and Joe Walsh, once a Tea Party-aligned Illinois congressman who is now a sharp critic of former president Donald Trump and supporting Vice-President Kamala Harris.
It was clear in the speeches and the party's touches that at least a few West Wing fans work in the White House.
The US Marine Band played the opening notes to the show's theme as Biden and the cast walked out.
There were references to "big blocks of cheese" - a show tradition of requiring staffers to meet with eccentric or offbeat characters - and the walk-and-talk dialogues in which characters moved through the halls at high speed.
Waiters passed out bourbon-and-ginger ale cocktails called The Jackal, a reference to press secretary CJ Cregg's dance and lip sync routine in one episode.
After Sheen's address, Sorkin recognised the cast members in attendance, among them Richard Schiff, who played communications director Toby Ziegler; Janel Moloney, who played assistant Donna Moss; and Dule Hill, who played the president's body man, Charlie Young.
He also noted the absence of a few high-profile actors - Allison Janney, Bradley Whitford and Rob Lowe - who he said were on set elsewhere.
"The rest of us are apparently unemployed," he joked.
After the crowd laughed, a voice chimed in from Sorkin's right.
"Not yet!" Jill Biden said.
