During her speech, Nikki Haley made an appeal to those who don't fully support Trump.

"My message to them is simple. You don't have to agree with Trump 100% of the time to vote for him," she said.

"Take it from me, I haven't always agreed with the president. But we agree more often than we disagree. We agree on keeping America strong," she continued.

She said a "unified Republican party is essential" for saving the country. She criticized President Joe Biden as showing "every possible sign of weakness" on foreign policy and Vice President Kamala Harris as contributing to the "border disaster."

"We are stronger when we welcome people into our party who have different backgrounds and experiences," she said. "Right now we need to be strong to save America. This is a defining moment, not only for our party but for our country."

11:38

Nikki Haley gives Trump her 'strongest endorsement' at RNC

Trump’s former campaign rival delivered a speech on the second day of the Republican National Convention in Milwaukee.

Nikki Haley, Trump’s biggest challenger in the 2024 Republican primary, was met with some scattered boos as she took the stage.

One woman seated in the crowd said, mockingly, “Now she’s going to dig herself out of the hole.”

But she got more of the audience on her side throughout her speech, and by the end, many stood up out of their seats and even tipped their hats.

-ABC News’ Alexandra Hutzler

Nikki Haley, Trump’s former GOP primary rival, officially endorsed the former president for the first time after walking out to applause and some boos.

"President Trump asked me to speak to this convention in the name of unity," Haley said. "I'll start by making one thing perfectly clear: Donald Trump has my strong endorsement, period."

Trump stood up to applaud.

Trump and other Republicans have pointed to the murder of Laken Riley and other recent crimes committed by undocumented immigrants as proof there's an ongoing migrant crime wave.

The reality is that there is no evidence that points to a major surge in crime caused by recent arrivals.

According to the latest FBI statistics, which are released quarterly, violent crimes were down 6% in quarter 4 2023 through December 2023 compared to the same time frame the previous year.

There was a 13% decline in murders, and a 4% drop in property crimes across the country. That declining trend followed unprecedented spikes in 2019 and 2020, Trump's last two years in office.

U.S. citizens also commit crimes at higher rates than undocumented immigrants, according to data.

A 2020 study in the Proceedings of the National Academy of Sciences showed U.S.-born citizens "are over 2 times more likely to be arrested for violent crimes, 2.5 times more likely to be arrested for drug crimes, and over 4 times more likely to be arrested for property crimes" than undocumented immigrants.