In the final days before the Iowa presidential caucuses in 2008, Joe Biden and his top advisers were still hoping for a third-place finish, or even a close fourth. In a late-night meeting as voting neared, a former congressman and local power broker they had summoned told them their hopes were unlikely to be fulfilled.

They had not tended to some of the most basic functions of a presidential campaign. Rather than recruiting legions of staff members and volunteers, or using his oratorical skills to inspire a grass-roots army, the Democratic senator was running a race like his Delaware campaigns, with a merry band of relatives and friends around him. The campaign had little money, starved of resources and momentum.

“You don’t have anyone on the ground,” Dave Nagle, the three-term congressman from eastern Iowa, remembers telling the Biden team.

A few days later, the campaign’s fifth-place finish was crushing. Biden received less than 1 percent of the vote. He carried none of the state’s 99 counties. And he dropped out immediately.

It was a rebuke of all that Biden had argued for, that experience mattered more than excitement. And it was his second unsuccessful effort at a presidential run — coming 20 years after he first entered the fray as a promising young senator but then soon backed out of the race amid allegations that he had plagiarized speeches.

Biden will return to Iowa on Tuesday, heading back to the scene of one of his most spectacular political failures, where many of the same issues may confront him and supporters hope he has learned from past mistakes.

As he begins his third presidential campaign, he faces stiff tests: He must show that he can control his own mouth, the vehicle for his destruction in his first two presidential attempts. He must demonstrate that his campaign is fundamentally improved — better financed, more organized — from 2008, when he was overrun by two contenders reaching for history, Sens. Barack Obama (Ill.) and Hillary Clinton (N.Y.). And he must hope that his party, which if anything seems to have moved further from him in the intervening years, wants what he offers.

In 2008, it did not.

“It was the wrong moment. We had qualifications; we were decent campaigners,” said Bill Richardson, a former New Mexico governor who finished ahead of Biden in Iowa that year. “I think we all knew from the reaction of Iowa voters that it was going to be a two-person race and those of us with résumés, with traditional backgrounds, weren’t going to make it.”

Biden’s new effort carries similar risks, he said.

“The challenges are that it could be that this year, Democratic voters want youth and new faces,” he said. “We’ll find out. If that’s the case, Joe will [still] be in contention. But it won’t be [as] easy.”

Biden’s first presidential campaign, for the 1988 nomination, began with significant promise. The senator from Delaware was a fresh face in his 40s, an up-and-comer in Democratic politics, his campaign compared to a rising meteor. Even though he hadn’t run in 1984, he still won a delegate’s vote at the Democratic National Convention.

But it didn’t last. Campaign infighting led to a variety of slogans and a muddled message. More-dispassionate rivals such as Massachusetts Gov. Michael S. Dukakis and Rep. Richard A. Gephardt (D-Mo.) gained strength.

Biden’s oratory was one of his advantages, which made it even more problematic when he was accused of using without credit lines from a speech by a British politician. Biden said it was an oversight, but reports emerged that he also had used lines from Robert F. Kennedy and Hubert H. Humphrey without attributing them. Biden also had been cited for plagiarism in a paper during law school, an error he blamed on not knowing how to properly cite sources.

Three and a half months after his campaign began, he dropped out, saying his decision stemmed from “the exaggerated shadow” of his mistakes.

“Although it’s awfully clear to me what choice I have to make, I have to tell you honestly, I do it with incredible reluctance,” he said. “And it makes me angry.”

Biden later regretted dropping out, suggesting to some around him that he should have fought back and stayed in the race. Those regrets may have contributed in recent days to his public reluctance to issue full apologies for his treatment of Anita Hill during the 1991 Supreme Court confirmation hearings for Clarence Thomas or for making women uncomfortable with close contact.

During an appearance on ABC’s “The View” on Friday, the five female hosts practically begged him to apologize on both counts. He instead equivocated.

Although the appearance showed the potential peril for Biden, it also demonstrated a strength that has marked all of his campaigns. He connected emotionally with the audience several times, no more so than when he spoke about grief and became emotional while discussing his elder son, Beau, who died of cancer in 2015.

Asked whether he was the motivating factor for this campaign, Biden said, “No, he’s not why I’m running. I hope — it sounds stupid. When I get up in the morning, I think about — I hope he’s proud of me. I hope he’s proud.” He wiped tears from his eyes.

Twenty years after the first Biden presidential campaign came the second, generously described by those involved in it as haphazard and free-flowing. It was unclear when the launch would occur, or even who would be campaign manager, until the last minute. Biden’s advisers were splintered into Senate staff and campaign staff; they often didn’t communicate with one another.

The day he announced his candidacy, his political staff was caught off guard by the publication of comments Biden made a week earlier in an interview with the New York Observer. In them, he called Obama “the first mainstream African American who is articulate and bright and clean and a nice-looking guy.”

The comments sent the campaign into a spiral. Biden held a conference call with reporters in which he expressed regret for his remarks but didn’t fully apologize. Some of the donors the campaign had hoped to sign up got cold feet.

“The campaign was technically over before it began,” said one adviser, speaking on the condition of anonymity to preserve relations with the former vice president. “Because it was starved of money throughout.”

Biden focused tightly on winning Iowa.

At one point, Nagle and his wife spent a day driving around to Biden events. The turnout was solid, they noted, and then they realized they were seeing the same people at every stop. In the final stretch, they went to an event in Dubuque where a respectable crowd of 300 had gathered. Obama showed up soon after and drew 1,200.

Biden’s campaign also seemed to care little for the voters it hoped would caucus for him in 2008. Aides would scramble from one event to the next, neglecting to sign up supporters for future contact, some who witnessed it said. Biden was, according to one high-ranking official on his campaign, overly focused on winning endorsements.

“The thing that plagued the Biden campaign in 2008 is they had a tendency to treat it like Joe was running for the Senate in Delaware,” Nagle said. “There was nothing wrong with the candidate. He was vigorous; he worked himself to exhaustion. He was a good candidate. . . . There just simply wasn’t a structure to support him and make sure he could be successful.”

He added: “When you’re running Delaware, you can do it with family members and old friends and get the job done.” But: “This ain’t Delaware. Nothing against Delaware, but running in Delaware is like running for the House. Running in Iowa is like running for president.”

One positive came out of his brief campaign and would pave the way for his third candidacy. Biden developed a bond with one of his competitors, Obama. Once Obama secured the nomination, he would turn to Biden to serve as his vice president.

Biden, 76, enters the 2020 race in a much different position from before. No longer running as a small-state senator, he carries the gravitas of the vice presidency under the last Democrat to win the White House. He hopes to draw a sharp contrast with a largely unpopular President Trump, who has scrambled the nation’s politics.

Biden’s calculations are that the landscape has so changed that he will find a receptive audience. Neither he nor his team blames Biden himself for his past inability to secure the nomination. The conditions, they argue, simply didn’t allow him to succeed.

“I don’t think there’s anything else Joe could have done in 2008,” said Buck Clark, a former mayor of Waterloo, Iowa, who backed him then and still does. “At that time, his age and length of time in politics worked against him. His age hurts him this time — but I don’t think it will hurt as much as it did in 2008, even though he’s obviously older.”

Some of those advising Biden now were with him during the disciplined Obama administration, which some longtime Biden observers consider a good thing.

Some of his longtime advisers also insist they are seeing a more careful Biden. During the first days of his campaign, he has bitten his tongue more than usual, if not completely. When he traveled through a pizza shop in Wilmington, Del., on Thursday, he batted away a number of questions rather than engage with reporters.

And during his interview on “The View,” fraught with suggestions that he apologize to Hill and any women he’d made uncomfortable with his actions, Biden began several times to defend himself before stopping and declining to answer further.

After suffering money woes in his 2008 campaign, he also has prioritized fundraising this time in a way that he hadn’t in the past. He has been calling donors to court them, and on Friday announced the largest campaign haul over the first 24 hours of anyone in the race: $6.3 million.

“I think now Joe has a good chance because the main criteria that Democratic voters want is someone who can beat Trump,” Richardson said. “And I think Joe qualifies there after a very good stint as vice president. His strongest asset is perception he’s blue-collar and can win.”