COLUMBIA, S.C. — Beto O'Rourke invoked the memory of Robert F. Kennedy as he spoke to South Carolina Democrats at the state party's convention with his signature campaign issue of immigration.

"We must heed the words of Robert Kennedy, who in 1967, the time of division and polarization, reminded us that no matter our differences we share one precious possession, and that is the name 'American,'" the former Texas congressman and 2020 Democratic presidential candidate said on Saturday.

"To be American, he said, is to have been a stranger, an outcast, to have come to the exiles' country, and to know that he who denies the outcast or a stranger, he also denies America," he continued. "So at this moment of truth, which will define us forever, let us not deny America. Let us celebrate and embrace America."

O'Rourke similarly referenced the 64th U.S. attorney general and younger brother of the 35th president, John F. Kennedy, during a pre-convention rally at Pearlz Oyster Bar. There he met supporters who walked with him onto the convention hall floor and surrounded him for the duration of his seven-minute address.

"Robert Kennedy, looking at the deep division and polarization in America reminded us that despite the difference we all have one precious possession in common: that is the name American, he said. And our opportunity, and really our obligation, to this and every generation that follows is to include everyone in that definition of American," he said during the earlier event.

Kennedy was shot and killed in 1968 while he was the lead candidate for the Democratic presidential nomination that year.

O'Rourke, at the convention, also spoke about the importance of gun control measures and universal healthcare, as well as investments in education and efforts mitigating the effects of climate change. He additionally attacked President Trump for hindering America "from living up to the full character, and potential, and promise of this country."

O'Rourke, who rose to prominence for narrowly losing his 2018 Texas Senate bid against Republican incumbent Sen. Ted Cruz, was initially hailed as an heir to the Kennedys. But the former fundraising powerhouse is struggling to leverage his popularity from last year into a successful run for the White House, attracting on average 3.6% support nationwide.