By Steve Holland and Susan Cornwell
Presumptive Republican US presidential nominee Donald Trump and House of Representatives Speaker Paul Ryan have emerged from a meeting declaring they have taken steps toward healing fissures in the party, but that differences remained.
Mr Ryan -- the nation's top elected Republican -- still hasn't endorsed Mr Trump, due to concerns over the billionaire businessman's incendiary tone and policy ideas, which run counter to longtime Republican doctrine.
He has opposed Trump's proposals to temporarily ban Muslims from entering the United States, deport 11 million illegal immigrants and impose protectionist trade policies.
Party leaders are normally eager to rally around a presidential nominee to combine forces for the battle leading up to November's general election.
The talks were aimed at finding common ground between the two, as Mr Trump seeks to rally party loyalists behind him.
"This was our first meeting, but it was a very positive step toward unification," the pair said in a joint statement.
Addressing journalists after the meeting, Mr Ryan said he was encouraged by the session, but stopped short of endorsing the 69-year-old New Yorker.
"There's no secret that Donald Trump and I have had our differences. We talked about those differences today," Mr Ryan said.
"I do believe we are planting the seeds in getting ourselves unified."
Mr Ryan, who may harbour aspirations of running for president in 2020 or later, noted that he represents a wing of the conservatives and that it is positive that Trump is bringing new voters into the party.
"The point, though, is: Can we agree on the common core principles that unite all of us?" he says.
After their private session Mr Trump and Mr Ryan attended a wider meeting with other Republican leaders.
Mr Ryan, 46, is seen as a leader of the party establishment that has resisted Trump's candidacy.
Outside the RNC headquarters, a knot of protesters took advantage of the heavy news media presence to denounce Donald Trump and the Republican Party with chants and signs that said "the GOP, Party of Trump."
An endorsement from Mr Ryan would help Mr Trump and the party move past an increasingly awkward phase, during which Republican officeholders and congressional candidates have publicly struggled with the decision of whether to support the New York real estate developer.
Mr Trump's campaign, however, has suggested Mr Ryan's support is not essential, pointing to the more than 10 million votes Mr Trump has received in party nominating contests.
Full support by leading party figures such as Mr Ryan would also help Mr Trump build the kind of campaign infrastructure and fundraising operation he may need to compete against the likely Democratic nominee Hillary Clinton in the November 8 election.