Five cardboard boxes were delivered to the Capitol Hill office of Arizona Sen. John McCain this afternoon. The boxes themselves were empty, but contained within them was a strong message: Republican leaders should publicly denounce Donald Trump.

Earlier this week, the advocacy group MoveOn.org, in partnership with the political action committee Common Sense Fund, gathered more than 102,000 online signatures in a petition urging McCain and other Republican leaders to un-endorse Trump for president. Today, at the Upper Senate Park near the Capitol building, representatives from the movement blasted Trump for his provocative rhetoric and misogynistic tendencies. Then they marched to the nearby Russell Office Building and delivered their request in person, in the form of a flash drive containing the signatures and five cardboard boxes symbolizing them.

The receptionist in McCain’s office greeted the display with bemusement, and admitted afterward that her colleagues had warned her earlier that day about the protest. “I’ll certainly pass that along,” she told the veterans. “Thank you for stopping in.”

Before that, five veterans delivered impassioned speeches detailing their military backgrounds and outlining a strong case that Donald Trump should not be elected president, using adjectives including “bigoted,” “reckless,” and “divisive.” Nate Terani, an Arizona resident and Navy veteran, noted that the United States military is one of the world’s most diverse and called upon McCain to exercise his “moral responsibility to denounce Trump’s hostile takeover” of the Republican party and the American political system.

Donald Trump’s repeated insults directed over the past week at the family of Humayun Khan, a Muslim American soldier who was killed in Iraq in 2004, fueled the growing frustration with the current election cycle from the veteran community, former Marine sergeant Alexander McCoy said. Trump’s earlier statements supporting military slaughters of civilians and recent support for using nuclear weapons also raised ire among the veterans.

The MoveOn.org activists selected McCain as the subject of their petition because of his record of military service and his recent public comments criticizing Trump without withdrawing his endorsement of the GOP candidate, according to the group’s media relations director Brian Stewart. Trump has also refused to endorse McCain, as well as House Speaker Paul Ryan.

President Barack Obama and others in the media have called upon Republican leaders to formally un-endorse Trump, particularly in light of the New York businessman’s recent statements. “If you are repeatedly having to say, in very strong terms, that what he has said is unacceptable, why are you endorsing him? What does this say about your party that this is your standard-bearer?” Obama told the press on Monday.

Planning for the rally came together in less than 48 hours, Stewart said. McCoy tells DCist that he and his fellow activists reached out to their network via Facebook groups and users of the hashtag #VetsVersusHate.

Former Navy nuclear machinist mate James Lyons of Rhode Island said he hadn’t prepared for the array of television cameras and other press attention. When he was rehearsing the speech on Monday and Tuesday, he found himself “stumbling and bumbling” over his word choices, and worried that he might crack under the pressure of the live event. But when the time came to deliver the speech, the words flowed easily.

“It became very easy at that podium,” said Lyons. “I was speaking from my heart.” He pointed out during his speech that he served on the U.S.S. Theodore Roosevelt and the U.S.S. Dwight D. Eisenhower, “named after two amazing Republican presidents.”

Pressed on their own political affiliations, the veterans said they disagree on who should be president but agree that it shouldn’t be Trump.

Few members of the general public showed up for the rally, but Stewart said he and his team had been more concerned with inviting members of the media. One passerby, a shoeshiner in the Russell Building who said McCain is a frequent customer, heard about the event for the first time while strolling through the park during his afternoon break.

Even without massive public attention, Terani feels the message has been sent. He says he wasn’t afraid of opposition to the event because of his deep-seated belief in the veracity of his message.

“I think when you’re doing the right thing, there’s no fear,” Terani said.