James E. Clyburn met the young senator from Delaware about 40 years ago, well before Joe Biden launched any of his three bids for president and decades ahead of his eight-year run as vice president.

The duo spent years tending to each other at times of personal despair and boosting each other at key moments — none more critical than Clyburn, 79, now the House majority whip and highest-ranking black member in Congress, bestowing his endorsement on Biden last week.

The former vice president’s campaign for the White House got off to a horrible start in early states and, by last week, support among African Americans remained wobbly — until Clyburn (D-S.C.) spoke up. Biden was lifted to victory in South Carolina on Saturday by winning more than 60 percent of black voters, a share he repeated in many states Tuesday, winning 10 of the 14 states on the ballot.

Despite all the doubts about Biden’s standing, the 14-term lawmaker said he knew who his constituents wanted to support, but they just needed the signal to rally around Biden.

“Get to know the people that you want to vote for you,” Clyburn said in a 30-minute interview Wednesday. “I knew that they were waiting to hear from me.”

With Biden in place as Democratic delegate-leader, Clyburn’s friends have spent the past 72 hours marveling at how the presidential race has pivoted from Sen. Bernie Sanders (I-Vt.), someone most Democrats have a cool relationship with, back into the arms of Biden.

“Jim Clyburn’s endorsement was an earthquake that will be written about in the history books,” Rep. Hakeem Jeffries (D-N.Y.), a member of Democratic leadership, said Wednesday morning.

For more than a week Clyburn and his red zip sweater, the color of his alma mater, South Carolina State University, have been ever-present on national TV, taking victory laps as a kingmaker. It’s an unfamiliar role for a man who has spent more than 17 years on the leadership team of House Speaker Nancy Pelosi (D-Calif.), usually following her lead.

“The country has now seen what we experienced working with Jim Clyburn day after day,” Jeffries said.

Clyburn, who said he would decline any job in a Biden administration, joked that he wanted to be “ambassador to the PGA,” a posting the avid golfer would have to first create.

Instead, he plans to file paperwork Friday to run for a 15th term in the House.

A civil rights activist as a youth, Clyburn was arrested for organizing a sit-in in 1960 in South Carolina. In jail, he met Emily England, a fellow college student who split a hamburger in two for them to share.

About 18 months later, they were married, and the first of three daughters was born in 1962.

By 1971, Clyburn became the highest-ranking black adviser to a South Carolina governor, and after a major speech in Charleston, he got in the car with his wife for the two-hour drive to Columbia. He finally asked what she thought.

“I just wonder when you’re going to stop talking about the problems of South Carolina and start doing something,” Emily Clyburn said, according to her husband’s recollection.

He set his sights on elective office, with stops and starts at the local level, until winning a newly drawn district in 1992 stretching from Columbia to Charleston.

He quickly became an influential figure in the Congressional Black Caucus and in 2003 won a junior post on Pelosi’s leadership team. When Democrats won the majority in the 2006 midterms, Clyburn became majority whip, a position that only one other Congressional Black Caucus member held.

Since South Carolina got this early spot on the quadrennial calendar, Clyburn has served as the ambassador to the state’s Democratic primary. He stayed neutral in the epic 2008 battle between Barack Obama and Hillary Clinton, but stepped in several times to criticize actions by Bill Clinton.

In 2016, Clyburn backed Hillary Clinton over Sanders just before the Nevada caucuses. She won Nevada and then won South Carolina in a landslide.

This time, Clyburn swore publicly that he would not endorse anyone until after the Feb. 25 debate in Charleston — but his friends say they knew where his heart was all along.

“He was always a Biden person. He always had great respect and admiration for Joe Biden,” Rep. G.K. Butterfield (D-N.C.), a former Congressional Black Caucus chairman, said Wednesday.

After meeting decades ago, Clyburn and Biden talked about their childhoods and Biden’s experiences around Wilmington, Del., a racially charged city in the 1960s and 1970s.

When they served in Congress together, Clyburn liked to appear alongside Biden, then a senator, on cable talk shows.

When Emily Clyburn died in September, after a long illness, Biden attended a service in Charleston for her, one of many presidential contenders who made the journey.

But as Biden’s campaign got started, Clyburn saw the same mistakes everyone else did.

Stories about Biden’s record on busing and allegations that he was too gregarious with supporters — sometimes kissing women on the forehead without asking permission — left him unsure of his instincts.

“He was out of kilter,” Clyburn said. “Joe Biden got knocked off stride.”

Two days before the debate, Clyburn met with Biden and gave him forceful advice, trying to clear his head of the many ideas aides gave him.

Answer every question, Clyburn told him, in three parts: Tell voters how an issue connects to their lives individually, to their family and then more broadly to their community.

Biden won fairly good reviews for being more focused than in previous outings, amid what was otherwise a shouting match.

The next morning, Clyburn ended what little suspense was left. “I know Joe. We know Joe. But most importantly, Joe knows us,” Clyburn said.

Butterfield said a close friend who worked for Tom Steyer, the billionaire businessman who spent more than $20 million in the Palmetto State, informed him that his share of the black vote plummeted.

“The minute Clyburn endorsed Biden, he could feel the ground shifting, because the black vote that Steyer had was soft,” Butterfield said.

Still, at this great moment of national acclaim, Clyburn feels a hole in his heart.

“We can have a private conversation, and we can say something that would remind him of Emily and something she had said to him. And he will just pause for a moment,” Butterfield said.

Late Tuesday, after another cable TV hit, Clyburn’s daughter texted to tell him that he looked exhausted, his eyes turning red from lack of sleep.

So, Clyburn told the Biden campaign that he cannot make it to Michigan to campaign this weekend, and he asked for some much-deserved time off.

“I’m going home to get some rest,” he said.