Merchandise supporting former US President and Republican presidential candidate Donald Trump on display during the second day of the 2024 Republican National Convention
Merchandise supporting former US President and Republican presidential candidate Donald Trump on display during the second day of the 2024 Republican National Convention AFP

Donald Trump returned to the Republican National Convention Tuesday for a night intended to unify the party, as his defeated rivals for the nomination lined up to heap praise on the official US presidential candidate.

Three of his former foes took the stage separately during prime time to publicly throw their support behind the former president, including one-time UN ambassador Nikki Haley who told delegates that "a unified Republican Party is essential for saving" the nation.

Trump, again wearing a white bandage on his ear that was injured in Saturday's assassination attempt, waved, shook hands and said "thank you very much" as delegates burst into an ovation.

While he made no formal remarks, the 78-year-old backslapped and chatted with his new running mate J.D. Vance and others, pumping his fist and looking more relaxed than during his emotional entrance the previous night.

The Republican leader has been widely feted at the four-day convention, where on Thursday he is set to formally accept his party's nomination as the flagbearer to challenge Democratic President Joe Biden in November.

Tuesday was an exercise in presenting a unified front, but the smattering of boos that echoed with cheers across the convention floor when Haley took the stage -- with Trump looking on -- suggested the party had work to do to gather the base's four corners for the final four months of a bruising presidential campaign.

Haley had antagonized Trump during the primary battle but on Tuesday she was clear: "Donald Trump has my strong endorsement, period."

Her fellow former Trump challengers -- Florida governor Ron DeSantis and businessman Vivek Ramaswamy -- also kissed the ring, with the latter telling the 2,400 Republican delegates: "Donald Trump is the president who will actually unite this country -- not through empty words, but through action."

Haley, who this year said the United States can't "go through four more years of chaos" under Trump, had not been expected to appear.

But Saturday's shooting at a Pennsylvania campaign rally reshuffled the deck, and Haley joined the speaking schedule along with Ramaswamy and DeSantis.

"Take it from me: I haven't always agreed with president Trump," Haley said, "but we agree more often than we disagree."

As Trump builds a coalition of rivals that he hopes will help him topple Biden, Haley's comprehensive endorsement may well give cover to her supporters to vote for the brash billionaire in November.

Seeking to reassure voters that he remains robust despite the traumatic attack, Trump's team announced he and Vance will address a campaign rally on Saturday afternoon -- just one week on from the incident.

Amid calls to lower the temperature of America's heated political rhetoric, US House Speaker Mike Johnson told the convention Tuesday that "we're not just uniting as Republicans, we're uniting today as Americans in the wake of the assassination attempt on the life of president Trump."

Meanwhile, Biden called for a ban on the type of semi-automatic rifle that was used in the attempted assassination.

"An AR-15 was used in the shooting of Donald Trump... It's time to outlaw them," the Democrat said during a campaign event in Las Vegas, adding: "Join me in getting these weapons of war off the streets of America."

Trump on Monday had solidified the Republican ticket by announcing Vance, a 39-year-old US senator from Ohio and a one-time harsh critic turned uncompromising supporter, as his running mate.

Vance, who says his modest Rust Belt upbringing makes him a voice for working-class voters in left-behind America, is set to address the convention Wednesday evening.

With Vance and Trump in the VIP box, and delegates giving off a joyous vibe, several speakers touched on the notion pervading the convention that divine intervention helped Trump escape assassination in Pennsylvania.

"God spared president Trump from that assassin, because God is not finished with him yet," Arkansas Governor Sarah Huckabee Sanders told the crowd.

Former Republican presidential candidate Vivek Ramaswamy
Former Republican presidential candidate Vivek Ramaswamy AFP
US former president and 2024 Republican candidate Donald Trump arrives at the convention
US former president and 2024 Republican candidate Donald Trump arrives at the convention AFP
Former Republican presidential candidate Vivek Ramaswamy (L) has endorsed Donald Trump as the party's 2024 White House nominee
Former Republican presidential candidate Vivek Ramaswamy (L) has endorsed Donald Trump as the party's 2024 White House nominee AFP