WASHINGTON ― President Barack Obama on Thursday awarded Vice President Joe Biden the Presidential Medal of Freedom, the nation’s highest civilian honor, during a surprise event at the White House paying tribute to him.

Moving Biden to tears, Obama hailed him as “the best vice president America has ever had” and “a lion of American history.” As he reached his concluding remarks, Obama surprised Biden by announcing the honor, a medal of freedom with distinction. The special version of the medal, Obama said, had been awarded under his three predecessors to only three other people: Pope John Paul II, former President Ronald Reagan and former Secretary of State Colin Powell.

"I am proud to award the Presidential Medal of Freedom with Distinction to my brother, Joseph Robinette Biden Jr." —@POTUS surprises @VP pic.twitter.com/Y8uB1W0fkG — The White House (@WhiteHouse) January 12, 2017

Biden, already teary during the tribute, began crying when the award was announced.

“I had no inkling,” Biden said, taking the podium after Obama awarded him the medal.

Obama honored Biden’s lifetime of public service, including his decades in the Senate and eight years as vice president. He pointed to Biden’s championing of the Violence Against Women Act, his diplomacy, his “cancer moonshot,” and his “It’s On Us” campaign to combat sexual assault on college campuses.

“That’s a pretty remarkable legacy, an amazing career in public service. It is, as Joe once said, a big deal,” Obama said, pausing between the “big” and the “deal.”

Obama’s tribute built on remarks he made during his Tuesday farewell address, when he called Biden his “brother.”

“To Joe Biden, the scrappy kid from Scranton who became Delaware’s favorite son: You were the first choice I made as a nominee, and the best,” Obama said in Chicago on Tuesday. “Not just because you have been a great vice president, but because in the bargain, I gained a brother.”

Both men have been outspoken about the deep friendship they have forged over their eight years in the White House, and Thursday’s event was no different, with both speaking in personal terms about each other and their families.

“Behind the scenes, Joe’s candid, honest counsel has made me a better president and a better commander in chief,” Obama said. “From the Situation Room, to our weekly lunches, to our huddles after everybody else has cleared out of the room, he has been unafraid to give it to me straight, even if we disagree. In fact, especially when we disagree. And all of this makes him, I believe, the finest vice president we have ever seen.”

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Biden called Obama “a remarkable man.”

“I tell everybody, and I have told them from the beginning, and I am not saying this to reciprocate: I have never known a president, and few people I have ever met in my whole life ― I can count on less than one hand ― who have had the integrity and the decency and the sense of other people’s needs like you do,” Biden said to Obama.

“I just hope that the asterisk in history that is attached to my name when they talk about this presidency is that I can say I was part of the journey of a remarkable man who did remarkable things for this country,” he added later. “Remarkable things.”

Of the honor, Biden said: “I don’t deserve this. But I know it came from the president’s heart. There is a Talmudic saying that says, what comes from the heart enters the heart. Mr. President, you have creeped into our heart, you and your whole family, including Mom, and you occupy it.”

CORRECTION: An earlier version of this article incorrectly stated that the Presidential Medal of Freedom with Distinction has only been awarded three other times. It has been awarded only three times by the previous three presidents.