"The meeting was great. It was a very positive step toward party unity," Priebus, one of the top Republicans meeting Trump along with House Speaker Paul Ryan, said in a tweet after their talks in Washington.
Ryan, the top-ranked Republican currently elected to public office, triggered soul-searching within a fractured party with the bombshell announcement last week that he was "just not ready" to support Trump as the flagbearer.
The concerns have trickled down to many in the congressional rank and file who fear a Trump nomination could doom their efforts to defeat Democrat Hillary Clinton in November and hold the majority in the Senate and House of Representatives.
"The goal here is to unify the various wings of the party around common principles," Ryan said on Wednesday.
"After coming through a very bruising primary, which just ended like a week ago, to pretend we're unified without actually unifying, then we go into the fall at half strength."
Chanting protesters greeted Trump as he arrived at the headquarters of the Republican National Committee in Washington for the sitdown.
He ignored the dozen or so protesters, who carried signs that read "Trump is a racist" and "RIP GOP," as he entered the building through a back door.