US House Speaker Paul Ryan has endorsed Donald Trump's bid for president, bringing an end to the extraordinary public split between the White House nominee and the nation's top Republican in office.
"I had friends wishing I wouldn't support him. I had friends wishing I would," Ryan said in an exclusive interview with The Associated Press.
"I really didn't feel any pressure, other than my goal is to make sure that we're unified so that we're at full strength in the fall so we can win the election."
Ryan's announcement, made in a newspaper column published in his Wisconsin hometown, marks a significant step for a Republican Party trying to come together ahead of a general election match-up against likely Democratic nominee Hillary Clinton.
And Ryan made clear he had Clinton on his mind when he decided to join the ranks of Republicans who have slowly come around to backing Trump, the brash billionaire few expected to emerge as the party's nominee when the campaign began in earnest last year.
"This to me is about saving the country and preventing a third progressive, liberal term, which is what a Clinton presidency would do," Ryan said.
Trump celebrated the endorsement on his favourite venue, Twitter.
"So great to have the endorsement and support of Paul Ryan," Trump wrote. "We will both be working very hard to Make America Great Again!"
There are still some GOP leaders who say they won't support Trump, including 2012 Republican presidential nominee Mitt Romney, who tapped Ryan as his running mate four years ago. A day earlier, Romney signalled that he'd support a possible third-party candidate instead of the presumptive Republican nominee.
Ryan himself acknowledged that he continues to have concerns Trump's combative style, but said after a series of conversations with Trump, he's confident he and the House Republicans he leads as speaker will be able to work with him as president on their agenda.
"We obviously have a different kind of style and tone. That's very clear. Anyone who knows anything about us knows that," Ryan said. "But what really, ultimately matters is how best can we make sure these principles and policies get enacted in 2017."
