Donald Trump will meet with Republican leaders in both the House and Senate when he visits Capitol Hill on Thursday.
Among those meeting with Trump will be House Speaker Paul Ryan, who last week said he was not yet ready to support the GOP's presumptive presidential nominee. Trump has threatened to protest Ryan's role as the head of the Republican National Committee this summer if Ryan does not support him.
Republican leaders in the Senate, including Senate Majority Leader Mitch McConnell, will also meet with Trump.
A senior Republican official told NBC News that Trump's tone and rhetoric will be discussed at the meetings. Along with Ryan, a number of prominent Republicans have yet to back Trump, and others have publicly said they won't support him.
Mitt Romney and former presidents George W. Bush and George H.W. Bush have announced they plan to skip the GOP convention in July.
"I never said never. I just said (not) at this point. I wish I had more time to get to know him before this happened. We just didn't," Ryan told the Milwaukee Journal Sentinel on Monday.
"We have right now a disunified Republican Party. We shouldn't sweep it under the rug without addressing it. That would be to our detriment in the fall," he added.