Nikki Haley to Speak at Convention as Republicans Aim for Show of Unity

Nikki Haley wasn’t invited to the Republican National Convention.

But after Donald J. Trump, her former boss and onetime rival for the Republican Party’s presidential nomination, was injured in an assassination attempt over the weekend, Mr. Trump’s campaign called and asked her to come. Ms. Haley obliged, and is set to take the stage Tuesday.

The moment is meant as a show of unity during a campaign that has highlighted rifts within the Republican Party — partly because of Ms. Haley’s hard-fought bid. The convention speech could also signal an important comeback for Ms. Haley, the former governor of South Carolina and former United Nations ambassador, who has kept a relatively low profile since she dropped her presidential bid this year.

“I think we ‘Make America Great’ by making us one, by making us whole, and I think it is very meaningful to have this opportunity for her,” said Kim Borchers, a Republican Party official from Kansas who voted for Ms. Haley. She added that Mr. Trump was doing exactly what Ms. Haley had asked him to do when she left the primary: reaching out to her strong base of supporters.

If Ms. Haley’s appearance is in prime time, that would also suggest that Mr. Trump is indeed ready to make amends, political strategists and convention attendees said.

But some of Ms. Haley’s delegates and supporters are now echoing her words to Mr. Trump when she left the race: This will now be Ms. Haley’s moment for choosing.

Many hope she will use her remarks to toe the line on the unity theme. They also want what many of her voters have always wanted — to see her stand for something, namely the more traditionally conservative values at odds with parts of Mr. Trump’s agenda. Perhaps the most prominent of those values has