WASHINGTON — President Obama bestowed the nation's highest civilian honor on Vice President Biden Thursday, calling his running mate and presidential understudy "the best vice president America has ever had."

The surprise State Room ceremony was alternately humorous and poignant, with Biden turning his face from the audience to wipe away his tears.

"I had no inkling," Biden said, saying he thought the event was supposed to be for first lady Michelle Obama. He jokingly fired his chief of staff for not telling him. "I don't deserve this, but I know this came from the president's heart."

The medal came with an additional rare honor: The Presidential Medal of Freedom with Distinction. That additional designation has been bestowed to only three others: Pope John Paul II, President Ronald Reagan and former secretary of State Colin Powell.

"It is, as Joe once said, a big ... deal," a straight-faced Obama joked, referring to Biden's expletive-laden remark on the passage of the Affordable Care Act.

"He has made me a better president, and a better commander-in-chief," Obama said. "When everyone else has cleared out of the room, he's been unafraid to give it to me straight, even when we disagrees. Especially when we disagreed."

Obama recited a list of Biden's accomplishments as vice president, leading the Middle Class Task Force, serving as the stimulus "sheriff," and manning "mission control" for the Cancer Moonshot. But he said those items do not capture the fullness of Biden's often-parodied persona.

"I have not mentioned Amtrak yet. Or aviators. Literally," Obama said. Joking about the close friendship they've had, Obama joked that one last joint event "also gives the Internet one last chance to talk about our bromance," he said.

Biden accepted the award with an off-the-cuff speech in characteristic fashion, reciting Irish poems, Talmudic sayings and inside stories. He told of the time, six months into his presidency, when Obama told him, "You know what surprised me is how we’ve come such good friends."

"I said, 'surprised you?'" Biden said. "That is candid Obama."

"There is no power in the vice presidency," Biden said. "There is no inherent power, nor should there be. But Mr. President, you have more than kept your commitment to me by saying to me you wanted me to help govern."