RNC officials said the calls were not prerecorded "robocalls."
Republican National Committee Chairwoman Ronna McDaniel and spokeswoman Kayleigh McEnany will attend the event, according to the Trump campaign.
Former RNC Chair Michael Steele warned that there would be "a lot of breast-beating and ugly tweets."
"He's not going to thank law enforcement because he's probably not happy about what law enforcement did," Michael Steele speculated.
Newly revealed emails of prominent Republican donor and billionaire Joe Ricketts include conspiracy theories regarding Barack Obama's citizenship and racist jokes.
Alt-right advocate James Allsup is now an elected official in Washington state as more white nationalists run for office than ever before.
"I thought about the Ramsey Rapist every night before I went to bed for five years," the former FBI director said.
Republican awards honoring conservative African Americans were absent the party's first black chairman.
The Republicans who stick by Trump are hastening their own disaster.
The outsider may have the establishment worried.
Aides to the candidates want control of the debates. Will the Republican National Committee be able to stay in the driver's seat?
Infighting over the debate process has split candidates, national committee.
Republican candidates are seeking control over how the debates are run.
The pledge is widely viewed as an effort to convince Trump not to run as a third-party candidate, a move which could strip away potential GOP voters.