Nikki Haley will speak on Tuesday
The former United Nations ambassador and South Carolina governor was the last major rival against Trump in this year's primary contest. She waited two months after dropping out in March to say she would vote for him. Then last week, she announced she would instruct her convention delegates to vote for Trump but wasn't planning to attend the convention.
It wasn't until Sunday - hours after the shooting - that her office reversed itself and said she would speak.
It's likely that she will call on her party to show cohesion in the face of this fall's general election battle against President Joe Biden.