Vice President JD Vance previewed a potential 2028 presidential campaign at a Republican gathering in Dallas on Thursday, delivering a message of nationalist pride to an enthusiastic pro-Trump crowd.Republicans are increasingly considering who could inherit President Donald Trump's political movement as the party confronts slipping approval ratings and uncertainty ahead of November's midterm elections.Trump, who followed Vance on stage, offered little immediate assessment of his vice president's performance, instead urging supporters to vote Republican on November 3.JD Vance and Donald Trump in Dallas (Getty)Later, aboard Air Force One, Trump told reporters Vance had done "very well," calling him a "very talented guy" and "a great vice president."Trump has not endorsed a potential successor, although Vance and Secretary of State Marco Rubio are widely discussed as possible 2028 contenders.Vance told the crowd Americans had an "American birthright" to safety and prosperity and portrayed Democrats as standing in the way."Don't give the country over to a bunch of crazy people because you happen to disagree with us on a policy issue here and there," he said.JD Vance gets a taste of 2028 as MAGA faithful chant ‘48’Vance's mostly scripted 40-minute address felt like a presidential nominating convention speech, in contrast to Trump's more freewheeling style.He went off-script when a protester raised a Mexican flag.Vice President JD Vance has offered to buy a protester who interrupted his speech at the Republican midterm convention a plane ticket to Mexico (Getty Images)"Well, my friend, if you love Mexico so much, get your ass over there," Vance said, prompting chants of "USA, USA, USA" before offering to buy the protester a plane ticket.Some supporters shouted "48, 48" — a reference to Vance potentially becoming the 48th president in 2028 — although Vance stressed that Republicans first needed to win November's midterms.Barbara Johnson, 58, of Plano, Texas, joined chants of "JD" and said Vance made a "pretty dang good argument" for becoming the party's next standard-bearer."He does have a gift and I think he is proving himself more and more that he could be the leader of the country," Johnson told Reuters.A protestor throws a Mexican flag at Dallas (AFP via Getty Images)Before Vance spoke, Republicans repeatedly portrayed Democrats as dangerous extremists. Texas Sen. Ted Cruz accused them, without substantiation, of forming a "new and dangerous red-green alliance" between communists and Islamists.The GOP tried to focus the convention on culture warsThroughout the two-day convention, Republicans sought to energize voters by focusing heavily on immigration, crime and cultural issues, frequently targeting Muslim politicians.Vance attacked the Biden administration's record, saying: "We were tired of being called racist for noticing that our country was becoming dirtier and poorer and less safe and less prosperous."Vance used his speech to target the Biden administration (AP)Far less attention was devoted to issues voters have identified as major concerns, including inflation, the cost of living and the U.S. war in Iran, which has pushed up fuel prices and lasted well beyond the four or five weeks Trump initially anticipated.Despite the hype, the convention reminded everyone that Trump is still the bossVance has traditionally aligned himself with the Republican Party's anti-interventionist wing and previously opposed conflict with Iran.Marking the first anniversary of conservative activist Charlie Kirk's death, Vance said, "Charlie hated war," but did not directly address the U.S. decision to enter the Iran war six months ago or distance himself from it.Vance referenced slain right-wing activist Charlie Kirk during his speech saying, “Charlie hated war” (Getty)Despite Thursday being billed as Vance's showcase, Trump remained visually dominant throughout the 20,000-seat arena. Giant photographs of the president covered the venue, including his raised-fist image following the assassination attempt in Butler, Pennsylvania.Trump then took the stage after Vance and, despite promising to be brief following his two-hour speech the previous night, delivered another 25-minute address dominated by familiar grievances against political opponents and the media.At one point, Trump had the audience repeat a phrase describing him as "the greatest president in the history of the United States."He ended with a blunt turnout message, telling supporters they would "go to hell" if they failed to vote in November.