Donald Trump was repeating his frequent call for Hillary Clinton's Secret Service agents to be stripped of their firearms when he added an aside to his rally remarks: "Let's see what happens to her."
Soon after, Mrs. Clinton's campaign said such a reference to violence was out of bounds.
The Republican candidate has long incorrectly said that his Democratic opponent wants to overturn the Second Amendment and take away Americans' right to own guns. In Miami on Friday, his riff about confiscating agents' guns went further.
"I think that her bodyguards should drop all weapons. They should disarm, right?" the candidate asked the crowd. "Take their guns away, she doesn't want guns. Take their — and let's see what happens to her. Take their guns away. OK, it would be very dangerous."
When given a chance to clarify his remarks, a campaign spokeswoman did not immediately respond.
But the Clinton campaign had a quick reaction. Clinton's campaign manager, Robby Mook, released a statement saying Mr. Trump "has a pattern of inciting people to violence. Whether this is done to provoke protesters at a rally or casually or even as a joke, it is an unacceptable quality in anyone seeking the job of Commander in Chief."
Mook added, "This kind of talk should be out of bounds for a presidential candidate."
A Secret Service spokeswoman declined to comment.
The seemingly ominous comment evoked a remark Trump made last month that many Democrats condemned as a call for Clinton's assassination. Speaking at a rally in North Carolina, the Republican nominee erroneously said Clinton wants to "abolish, essentially, the Second Amendment."
He continued: "By the way, if she gets to pick her judges, nothing you can do, folks. Although the Second Amendment people, maybe there is, I don't know."
Within minutes, the Clinton campaign condemned the remark. Mook said then, "A person seeking to be the president of the United States should not suggest violence in any way."
Trump later disputed that criticism, saying everyone in his audience knew he was referring to the power of voters and "there can be no other interpretation."
The businessman-turned-candidate, who has the endorsement of the National Rifle Association, eventually took to Twitter to say the Secret Service had not contacted him about the remarks.
Many of his campaign events have been marked by acts and threats of physical violence, as The Christian Science Monitor's Peter Grier noted in March:
Yet Trump hasn’t forcibly condemned supporter violence. If anything he’s appeared to condone it. “I’d like to punch him in the face,” Trump said of one protester at a February rally. Asked at Thursday night’s GOP debate whether he’s to blame for the most recent rally assault, Trump said he hoped not. Then he said in essence that the protesters deserve it.
“We have some protesters who are bad dudes, they have done bad things.... They’ve got to be taken out, to be honest. I mean, we have to run something,” Trump said.
His comments Friday came hours after he finally reversed his long-held position that President Obama was not born in the United States. Appearing in Washington, he said Mr. Obama was born in the United States but then incorrectly said that Clinton's 2008 campaign staff had started the conspiracy theory.
Trump ignored questions from reporters about his switch and has yet to explain why he adopted or abandoned the "birther" stance that fueled his political fame and was viewed by critics as an attempt to delegitimize the nation's first African-American president.
While campaigning in South Florida, which has a large Cuban-American population, Trump also said that if he's elected president, he will reverse Obama's efforts to normalize relations with Cuba — unless the country abides by certain "demands." Among those, he said, would be religious and political freedom for the Cuban people and the freeing of all political prisoners.
He'll "stand with the Cuban people in their fight against communist oppression," he said.
The comment marks yet another reversal for the GOP candidate, who previously said he supported the idea of normalized relations, but wished the United States had negotiated a better deal.
He also said the US has a broader obligation to stand with oppressed people — a comment that seems at odds with his "America first" mantra. "The next president of the United States must stand in solidarity with all people oppressed in our hemisphere, and we will stand with oppressed people, and there are many," he said.
He added that the people of Venezuela "are yearning to be free, they are yearning for help. The system is bad. But the people are great."
He has often cited the country as a model of a failed state, warning that if Clinton is elected, she'll turn the US into Venezuela.
Associated Press writer Jill Colvin in Washington contributed to this report.