WATCH J.D. Vance Speak at RNC - Unity on Display as Trump's Campaign Rivals Fight FOR Him

The Republican National Convention re-convened Tuesday night with a focus on securing America's borders and a show of party unity. Donald Trump's former campaign rivals gave back-to-back speeches, urging Republicans to come together to beat Joe Biden. 

"Let's make the 45th president of the United States, the 47th president of the United States," said Gov. Ron DeSantis (R-FL) who dropped out of the race for the White House back in January.

DeSantis praised Trump's record during his Tuesday night speech. 

"Our border was safer under the Trump administration and our country was respected when Donald Trump was our Commander-in-Chief," he said to the RNC crowd. 

WATCH RNC LIVE: JD Vance Expected to Speak

Trump's strongest challenger and tough critic during the campaign, his former UN Ambassador Nikki Haley, also pledged her support during a convention speech.

"You don't have to agree with Trump 100 percent of the time to vote for him," she said.

After endorsing Trump, Haley talked up his foreign policy record, making her strongest comments in support of the former president this election season.

"When Barack Obama was president, Vladimir Putin invaded Crimea. With Joe Biden as president, Putin invaded all of Ukraine. But when Donald Trump was president, Putin did nothing. No invasion. No invasions. No wars. That was no accident," Haley said.

Texas Sen. Ted Cruz, a rival from the 2016 campaign, praised God for protecting Trump from the weekend assassination attempt, and then turned to the situation on the southern border. 

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"11.5 million people have crossed our border illegally under Joe Biden. Look around you. This arena holds about 18,000 souls. Now imagine 639 arenas just like this, filled to the brim. That is 11.5 million people. Larger than all but eight states in the nation," he said.

Meanwhile, in an emotional speech, Lara Trump, RNC Co-Chair and Donald Trump's daughter-in-law, gave a description of Saturday's assassination attempt.

"Our family has faced our fair share of death threats, mysterious powders sent to our homes, tasteless and violent comments directed towards us on social media. But none of that prepares you as a daughter-in-law to watch in real time, someone try to kill a person you love," she said. 

Trump's new Vice-Presidential pick J.D. Vance takes center stage on Wednesday when the theme will be "Make America Strong Again." He's also expected to touch on border security, as well as the threat from China.