The Republican House speaker Paul Ryan and Donald Trump said after meeting Thursday in Washington they had taken a "very positive step" towards bridging party divisions sparked by the billionaire's White House bid.

"There's a great opportunity to unify our party and win this fall, and we are totally committed to working together to achieve that goal," Trump and Ryan said in a joint statement.

"This was our first meeting, but it was a very positive step toward unification," added the text, which fell short of a formal endorsement by Ryan of the presumptive Republican nominee.