President Obama said he and successor-in-waiting Donald Trump had an "excellent conversation" Thursday as the intense rivals who largely defined the volatile 2016 election discussed the hand-off of the White House.

The president said his "number one priority" over his last two months in office is to facilitate the transition to the Trump administration.

Trump noted that the Oval Office meeting was supposed to run for 15 minutes, but went closer to 90 minutes.

"As far as I was concerned, it could have gone on longer," the president-elect said.After searing rhetoric on the campaign trail — Obama called Trump dangerous, while Trump described the incumbent as perhaps the worst president ever — the two men struck conciliatory notes in the wake of Tuesday's surprising election results.

"It's time for America to bind the wounds of division," Trump said during his victory speech early Wednesday.

Obama is "quite sincere about fulfilling the basic responsibility that he has to the American people and our democracy to ensure a smooth transition to the next presidency," said White House press secretary Josh Earnest.

After his meeting with Obama at the White House, Trump heads to Capitol Hill to meet with another key player in his emerging presidency, Republican House Speaker Paul Ryan. The vice president-elect, Mike Pence, will also attend the session with Ryan, who, like Obama, had his share of differences with Trump.

The president-elect is starting to speak with an array of foreign leaders by phone, from Japan to Turkey. British Prime Minister Theresa May congratulated Trump on his victory, and reminded the New York businessman of his "commitment in his acceptance speech to uniting people across America, which she said is a task we all need to focus on globally," according to a statement from May's office.

Trump invited May to visit him as soon as possible, the statement said.

Another world leader, Canadian Prime Minister Justin Trudeau, announced his government is prepared to re-negotiate parts of the North American Free Trade Agreement with Canada.

The Trump team is also putting together possible picks for the Cabinet and White House staff.

While Obama and Trump spoke in the Oval Office, first lady Michelle Obama gave a tour of the residence to Melania Trump.

In preparing for his sit-down with Trump, Obama said "it is no secret" that they have "some pretty significant differences." But the president added that he'd also had differences with his predecessor, George W. Bush, and they had a smooth transition. He said he has instructed aides to "follow the example that President Bush's team set eight years ago, and work as hard as we can to make sure that this is a successful transition for the president-elect."

One Trump backer and Obama critic, former House speaker Newt Gingrich, described the meeting between the president and his successor as "an amazing tribute to the power of the people."

Trump spend much of his insurgent campaign pledging to reverse and tear down Obama's legacy. He called for repealing and replacing the president's health care law, voiding the Iran nuclear deal and ending new business and environmental regulations.

On the stump, Trump also criticized Obama for campaigning so much on behalf of Democratic nominee Hillary Clinton, saying he should "do the job he's supposed to be doing."

In his campaign speeches, Obama cast Trump as an erratic and perhaps unstable political novice who shouldn't be allowed near the nuclear codes. "It's really bad being arrogant when you don't know what you're talking about," Obama said.

The Obama-Trump rivalry, intrinsic to the 2016 election, goes back years.

During Obama's first term, Trump made a name for himself by becoming the de facto leader of the so-called "birther" movement, pushing the false idea that the president was not born in the United States. In this past campaign year, Clinton described the birther movement as a racist attack on the nation's first African-American president.

In 2011, Obama responded by producing a long-form birth certificate and mocking Trump at a high-profile press dinner as the New York businessman sat in the audience.

At the White House on Wednesday, Obama said he wants to make sure the presidential succession is "well executed because ultimately we're all on the same team."