After bashing Trump in primary, Haley and DeSantis to preach unity at Republican National Convention

MILWAUKEE -- Florida Gov. Ron DeSantis and former U.N. Ambassador Nikki Haley -- two of former President Donald Trump's fiercest competitors during the GOP primary who regularly told Americans he shouldn't get a second term -- are set to speak at the Republican National Convention on Tuesday night where they are expected to say just the opposite.

Sources told ABC News that DeSantis and Haley will take to the stage in what many view as an effort to unify the party behind Trump.

During the primary, both Haley and DeSantis said that if Trump were to be the GOP nominee again, Republicans would risk losing in November.

DeSantis repeatedly said that if Trump becomes the GOP nominee again, he would not win against President Joe Biden and often questioned how he would win back voters he lost in 2020.

"What's his path to victory?" DeSantis asked during a campaign event in Iowa in December 2023. "I mean, he was the incumbent president in 2020, couldn't get the job done. Now, he's out of office. How is he going to be able to do better this time? Who are the voters out there that have not voted for him in the past that all of a sudden they're going to be running back to want to vote for him?"

When it came down to Haley and the former president in the GOP primary, she went even further than DeSantis in her attacks on Trump.

In a Wall Street Journal interview in February, Haley says it would be "like suicide for our country" for the GOP to nominate Trump a third time.

The attacks between the two eventually turned personal, with Haley questioning Trump's mental fitness -- often calling for him to take a cognitive test -- while Trump attacked her husband.

In February, Trump mockingly questioned where her husband -- Maj. Michael Haley -- was, seemingly implying that there is something awry with their marriage and that was the reason he had not been with her on the campaign trail.

SEE MORE: RNC 2024 Day 2 live updates: Ramaswamy urges crowd to 'vote Trump'

Haley responded to Trump's comments about the whereabouts of her husband, who was on active-duty deployment in the Horn of Africa for the South Carolina Army National Guard at the time, calling him "unhinged."

However, both Haley and DeSantis would go on to suspend their presidential campaigns, making Trump the presumptive nominee.

DeSantis endorsed Trump when he ended his presidential bid -- but Haley took a different approach. She told her supporters it's up to Trump to win over voters and chose not to endorse the former president when she suspended her campaign.

"It is now up to Donald Trump to earn the votes of those in our party and beyond it, who did not support it," she said in March. "And I hope he does that. At its best, politics is about bringing people into your cause, not turning them away. And our conservative cause badly needs more people."

But a few months later, Haley shocked people by announcing she would be voting for the former president in November.

During a question-and-answer session after delivering a speech at the Hudson Institute in Washington, D.C., in May, Haley was asked who she thinks would do a better job in the White House with national security issues: Biden or Trump.

She said she prioritized a president who will hold enemies to account, secure the border and support "capitalism and freedom" -- and that while "Trump has not been perfect on these policies," that "Biden has been a catastrophe."

"So, I will be voting for Trump," Haley said.

While Haley has not actively participated in Trump's reelection campaign, DeSantis has helped to raise money for his campaign.