Trump Jr. was one of the campaign's potent tools in 2016, frequently sent out to small towns and rural areas where the Republican candidate looked to turn out disaffected voters who hadn't cast ballots in years. An even more aggressive campaign schedule is in the works for 2020.

"He's the future," said Annie Davidson, 65, of Alamo Heights. "He's just like his father and I can't wait to vote for him someday too."

By far the most outspoken of his siblings, Trump Jr. has never shied away from a political fight, even when it leads some to question his own sense of self-awareness.