How do you gift your popularity to someone else? As Barack Obama rolls up his sleeves to ensure Hillary Clinton succeeds him in the White House, his argument increasingly boils down to a simple message: Do it for me.

With approval ratings almost unheard of for an outgoing leader — 54 percent, according to the latest Gallup average — the Democratic president is hitting the trail full-time to help Clinton lock in crucial battleground states in the final stretch of the race.

Obama’s time this week is devoted almost exclusively to drumming up the vote for his former secretary of state in a marathon that started Tuesday in Columbus, Ohio, heading Wednesday to Raleigh, North Carolina, on to Miami and Jacksonville, Florida on Thursday and finally back to North Carolina’s Charlotte on Friday.

His stump speech is well-rehearsed. It starts with an avalanche of compliments for Hillary, summed up thus: “There has never been a man or a woman — not me, not Bill, nobody — more qualified than Hillary Clinton to serve as president of the United States of America.”

And it includes an arsenal of pointed attacks on her rival Donald Trump, in a nutshell: “The Republican nominee is unfit to serve as president.”

But Obama — who is well aware that Clinton struggles to whip up passion in the electorate — also regularly takes the conversation into more personal territory, linking her political future to his own legacy.

“I ask you to do for Hillary Clinton what you did for me. I ask you to carry her the same way you carried me,” he urged supporters in his address to the Democratic National Convention in July.

A few weeks later, America’s first black president went further by urging African Americans to mobilize for Clinton — telling them he would “consider it a personal insult” if they fail to rally this time around.

– Turn out the black vote –

Black voters traditionally lean heavily Democratic in the United States — and more than 90 percent voted for Obama in 2008 and 2012.

The crucial question facing the 69-year-old Clinton is whether she can draw anywhere near the historic turnout levels among black voters seen for Obama.

And so the president is flooding the airwaves in the homestretch of the race, hammering home the point Wednesday morning on the Tom Joyner Morning Show, a radio program whose audience is largely African American.

Obama cited the data coming in from early voting states, and issued a wake-up call: “I’m going to be honest with you,” he said. “The Latino vote is up. Overall vote is up. But the African-American vote right now is not as solid as it needs to be.”

It is not unknown for a serving president to dive into the campaign for his succession, but the intensity of Obama’s involvement has no equivalent in recent American history.

“(Dwight) Eisenhower stressed continuity with (Richard) Nixon in 1960 and so did (Ronald) Reagan with (George H.W) Bush in 1988, but no other president has been quite so personal in his appeal before,” said Larry Sabato, a political analyst from the University of Virginia.

On Tuesday night, as he addressed a packed, youthful crowd at Capital University in Columbus, Obama urged the electorate that carried him to power to “work as hard for her as you worked for me.”

“She made me a better president and she didn’t ask for credit,” said the president, campaigning in shirt sleeves and plainly savoring the heady campaign atmosphere that will soon be behind him.

“I am asking you just what I asked you eight years ago. I am asking to believe in your ability to bring about change,” he said, urging the crowd, in an echo of his history-making 2008 campaign, to “Choose hope!”