Rosie O’Donnell at the White House protest Monday night. Photo: Nicholas Kamm/AFP/Getty Images

The signs, a crucial element of any anti-Trump protest, had a Broadway theme at Monday’s White House protest.

“Book of Moron,” said one, which melded the The Art of the Deal’s book jacket and a musical you can probably guess. “The Liar King” had Trump’s face pasted onto Simba’s head. “Don Jr. was in the room when it happened” — Hamilton and that controversial 2016 Trump Tower meeting merged into one.

Ever since the Helsinki summit between President Trump and Russian president Vladimir Putin, protesters have flocked to D.C.’s Lafayette Park — smack in front of the White House, which they’ve dubbed the #KremlinAnnex — to make daily noise. Monday was the first time it was musical.

More than 50 Broadway performers from the casts of currently running shows — Hamilton, Wicked, Beautiful, SpongeBob SquarePants: The Broadway Musical — led by actress, theater supporter, and longtime Trump adversary Rosie O’Donnell showed up at the Annex to lend their alto, soprano, tenor, and bass voices to the cause.

“Let the president know in no uncertain terms that we are alive, awake, and we are woke,” O’Donnell told the crowd before the singing began. “And we are not going away.”

Conducted by Seth Rudetsky, the afternoon host on SiriusXM’s Broadway channel who also helped organize the New York–to–D.C. trek, the group then broke into “America the Beautiful,” followed by “Brand New Day” from The Wiz, “Climb Ev’ry Mountain” from The Sound of Music, “Do You Hear the People Sing?” from Les Misérables, and “Let the Sunshine In” from Hair. Lyric sheets were distributed beforehand to those who had gathered, so amateurs and professionals alike could join in.

.@Rosie protesting with Hamilton and speaking the truth: “People have just really had enough.”

pic.twitter.com/uTqWCzsWxk — Christian Cowart (@dtxErgaOmnes) August 7, 2018

The promise of a mini cabaret attracted a sizable crowd of, by this writer’s estimate, at least 200 protesters, theater geeks, and interested onlookers to the Annex. This was the rare demonstration where it was possible to see a pair of dancing T. rex; people holding light-up letters that spelled TREASON; Kristin Mink, the teacher and mother who famously confronted Scott Pruitt in a restaurant and told him to resign; and, also, Richard Kind.

“This is probably the most people we’ve had,” said Eleanor “Echo” Ory, a D.C. resident who has been at the protest every single night for the past three weeks.

Ory added that the protests helped energize people for the midterms, something on the minds of those who spoke in between songs, including Jim Obergefell, one of the plaintiffs in the lawsuit that led to legalizing marriage equality in 2015.

“We need to get this illegitimate president out of our House,” he said. Referring to the #LoveWins hashtag born out of the gay-marriage victory, he added, “It won back on June 26, 2015 and it must continue winning.”

In some cases, the chaos of the protest lent fuel to its political aims. In the middle of Mink’s remarks, a crying young boy who had gotten separated from his parents emerged from the crowd. Organizers, including O’Donnell and Mink, jumped in to help him reconnect with his mom and dad.

“It is distressing to see a child without a parent for five seconds,” Mink shouted afterward. “What kind of administration is it that allows to have hundreds, thousands of parents without their children for months, maybe forever?”

In other words, there was a bit of organic political theater to go with the actual theater. As for the latter, the performances wrapped after about a half hour, with O’Donnell & Co. marching all the way back to their bus, parked on H Street NW, still singing “Let the Sunshine In.”

“We’re gonna come again on a Monday when Broadway is dark,” O’Donnell promised the crowd before the group departed, suggesting this won’t be the last time that the Great White Way makes its way to the White House.