Former U.S. Ambassador to the United Nations Nikki Haley speaks on Day 2 of the Republican National Convention (RNC), at the Fiserv Forum in Milwaukee, Wisconsin, U.S., July.16, 2024. / Reuters/Elizabeth Frantz

MILWAUKEE (Reuters) -Donald Trump's former leading rivals for the Republican presidential nomination, Nikki Haley and Ron DeSantis, offered full-throated endorsements of his candidacy at the party's convention on July.16, a display of unity three days after Trump survived an assassination attempt.

Haley, who had described Trump as unelectable and unfit for office during her campaign, nevertheless urged her supporters to vote for him over Democratic President Joe Biden "for the sake of our nation."

"You don't have to agree with Trump 100% of the time to vote for him," the former U.N. ambassador and South Carolina governor said, after taking the stage to a mixture of cheers and boos. "Take it from me."

DeSantis, the conservative Florida governor whose campaign sputtered early in the year, received a warm welcome from the crowd as he attacked Biden as too old for the job.

Trump smiled and applauded from his box in the arena, where he sat alongside the running mate whose selection he unveiled on July.15, Senator J.D. Vance, himself a former fierce Trump critic who has become a staunch supporter.

The show of harmony was intended to contrast with the Democratic Party, which has spent weeks mired in intraparty tensions over whether Biden, 81, should abandon his reelection bid after his halting June.27 debate performance against Trump, 78, raised fresh questions about his age and mental acuity.

The tenor of the evening's speeches in Milwaukee - centered on the theme of safety - was more aggressive than the first night, with speakers angrily denouncing Biden's southern border policies as putting the country's security at risk. Kari Lake and Bernie Moreno, who are running in high-profile U.S. Senate races in Arizona and Ohio, respectively, and U.S. Senator Ted Cruz of Texas all called the flow of migrants an "invasion."

Cruz delivered remarks suffused with Trump's anti-immigrant rhetoric, blaming Democrats for what he said was a wave of violent crimes committed by migrants.

While border crossings reached record highs during Biden's tenure, arrests dropped sharply in June after the president implemented a broad asylum ban. Studies show immigrants do not commit crime at a higher rate than native-born Americans.

Trump has vowed to crack down on illegal immigration and pledged to launch the largest deportation effort in U.S. history, including the use of federal troops if necessary.

The divisive tone contradicted the message of national unity Trump had promised to deliver this week after the shooting.

Trump entered the arena around 8 p.m. local time (0100 GMT on July.17) to a raucous ovation, just as he did on July.15 in his first public appearance since a gunman tried to assassinate him on July.13 at a Pennsylvania campaign rally. He was more ebullient than the night before, when he seemed emotional and more subdued than usual. A heavily bandaged ear served as a reminder of how narrowly he survived the attempt.

BIDEN IS 'ALL IN'

The shooting intensified fears among Americans about the deeply divided state of the nation ahead of the November. 5 election.

A Reuters/Ipsos poll released on Tuesday found that 80% of voters - including similar shares of Republicans and Democrats - agreed "the country is spiraling out of control" in the wake of the shooting.

Authorities were still trying to identify a motive for the shooting. The 20-year-old gunman was killed at the scene by the U.S. Secret Service.

Vance, 39, the author of the bestselling memoir "Hillbilly Elegy," will deliver the headlining speech on July.17. His presence on the ticket is likely to energize core Republican voters, but it is less clear whether he can appeal to more moderate voters, including independents.

The Reuters/Ipsos poll found 29% of U.S. voters, including 52% of Republicans, had a favorable opinion of Vance. By comparison, 42% of registered voters and 81% of Democrats had a favorable view of Biden's running mate, Vice President Kamala Harris.

The survey of 992 registered voters, conducted on July.15 and 16, found Trump leading Biden by 43% to 41%, within the margin of error.

In his first campaign speech since the assassination attempt, Biden told Black voters in Las Vegas that he was "all in" for his reelection campaign, again dismissing calls from some Democrats to step aside.

The president said he was glad Trump had not been seriously injured but assailed his record in office. Biden has denounced the attack and called for less heated rhetoric.

The four-day convention will culminate with Trump's prime-time address on July.18, when he formally accepts the party's nomination to face Biden in a rematch of their 2020 race.