WASHINGTON — Hillary Clinton’s Boeing 737 campaign charter was swapped out for a sleek little private jet. Gone were the hundreds of staff. The motorcade shrank to just a few cars.

It was the summer of 2008, and Clinton — along with her downsized entourage — barnstormed the country for a man they had spent the past year-and-a-half trying to defeat.

Reminders of the demotion from candidate to surrogate surrounded them wherever they went. Barack Obama’s signs replaced hers. Women along the rope lines approached her in tears, saying: It should have been you.

As ever, Clinton carried on.

“I was amazed at her ability to dust herself off,’’ recalled Kathleen Strand, one of the handful of staff members who stayed with Clinton through the end of the 2008 general election. “It wasn’t so easy for me after the long fight for the nomination, but she had this ability because she knew it was what had to be done.’’

Clinton and her husband would attend about 100 events including fund-raisers, rallies, and media interviews, pitching Obama in the 156 days from when she conceded to him in June to the November general election.

The decision to bow out and work to elect her rival set her on the course that brings her to Philadelphia this week to claim the most significant prize of her long career: the Democratic nomination for president.

Propelling her were a steely determination and grit that are among her most consistent traits in 25 years of public life. Supporters at Clinton rallies from Iowa to Ohio cite her toughness, the long narrative of her successes after failures, when they explain their enthusiasm for her.

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Clinton, ever the pragmatist, had held onto her seat in the Senate, even as she mounted her White House campaign, and planned to stay in politics. It’s an occupation, like many, that rewards knowing when the best move is to choke down your pride and back the winner. Her career shows a willingness to be flexible and accept setbacks on the road to her goal.

“I’ve had a blessed life, but I also know what it’s like to stumble and fall,’’ Clinton says on the campaign trail. “And so many people across America know that feeling. And we’ve learned that it’s not whether you get knocked down that matters, it’s whether you get back up.’’

But her singular, stubborn determination to press on in her own way, no matter what, also runs through some of Clinton’s worst moments and judgment calls, including her insistence that she and top staff use a private e-mail server while at the State Department and her decision to charge six-figures for speeches at nonprofits, colleges, and some of the country’s largest financial institutions.

People close to Clinton, who stood with her through defeats and victories, marvel at her ability to keep going despite the headwinds that always seem to accompany her.

“You could not be her and do what she does for all of these years, or take the abuse that she has taken, without wanting to do good work,’’ said Randi Weingarten, the president of the American Federation of Teachers and a longtime Clinton friend. “There is no other explanation for that.’’

In Arkansas, after her husband was elected governor, Clinton chiseled out a law career for herself at a time when most women of her station didn’t work. It made her a curiosity in the courtroom — other lawyers recall stopping and watching her deliver arguments in far-flung Arkansas counties just because it was so rare to see the governor’s wife working.

The most searing public humiliation she endured — and one that Republican nominee Donald Trump continues to taunt her with to this day — was her husband’s repeated infidelity.

But when that pattern of boorish behavior eventually led to scandal and Bill Clinton’s impeachment, Hillary Clinton didn’t turn away from the public spotlight, as some thought she might. She sought to join Congress, the very institution that had just publicly humiliated her family.

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To endure such public scrutiny, Clinton’s friends say, she has constructed thick personal armor that both protects her and also makes her less accessible — harder for many to connect with as a person, harder to know or fully trust.

“Hillary is a proud woman,’’ explained former Clinton administration labor secretary Robert Reich in his 1997 book “Locked in the Cabinet.’’

Reich, a longtime friend of both Clintons who had a front-row seat to the early phases of the Clinton scandals, saw firsthand how Hillary Clinton’s armor could also become a political weakness, a barrier to forming bonds with voters.

“She doesn’t take sympathy well,’’ Reich wrote. “She’s so intent on seeming strong that she doesn’t realize how much hurt and anger she shows just below the surface.’’

“She somehow managed to survive it without the kind of scars or bruises most of us would feel having gone through that,’’ Reich said in an interview with the Globe, referencing the impeachment scandal. “It was very brutal.’’

The moment most associated with Clinton’s determination — and the legislative accomplishment she touts the most on the campaign trail — is her contribution to health care reform, a contribution that continued despite an earlier devastating defeat.

It’s hard to imagine now, but Clinton’s decision to even broach the subject publicly in 1998 wasn’t an easy one. That’s because her initial attempt had failed spectacularly four years earlier when the Health Security Act (or HillaryCare, as she likes to call it) was blocked without even a formal vote in the Democratic Senate.

It took years after that humiliation for Hillary Clinton to make her first big public speech on the topic. When she did, she selected an audience that would have been familiar with her mottled record on the subject: the 1998 graduating class at Harvard Medical School.

In her remarks, she acknowledged failure but also started talking about the incremental but meaningful steps her husband’s administration had taken afterward.

“There was a lot of trepidation,’’ recalled Neera Tanden, a top policy adviser to the first lady. “People were saying she should never talk about health care again. It was not an easy speech for her emotionally. The health care battle had been a searing thing.’’

Drafts of the 25-minute speech flew around the West Wing, with notes and suggestions. Ira Magaziner, who’d been instrumental in the failed attempt at a comprehensive health care overhaul, cleared a Sunday to rework a policy section of the speech after he acknowledged in a memo that the draft was “kind of boring.’’

Various staff members suggested jokes about Harvard and Yale to lighten up the subject matter. One note simply called for “more funny stuff.’’

But the guts of the speech — which saw multiple rewrites — focused on the failure of the Health Security Act. “People often ask: Were we disappointed about failing to pass comprehensive health care reform in 1994? Of course we were. Among Washington pundits it is considered one of our greatest failures,’’ according to one draft.

Then Clinton explained to the graduating class how she’d changed her goals to move forward, laying out a political philosophy that she employs to this day. “When the political environment makes it impossible to take large steps, you have two choices — take small steps or sit on the sidelines and do nothing at all.’’

What the speech didn’t say was that the first lady, that “proud woman,’’ had to accept something else: a diminished role in the pursuit of those smaller goals.

When the White House continued the push for health care reform, Clinton wouldn’t be one of those testifying before Congress. She wouldn’t be appearing on Sunday shows selling the next steps to the public. She wouldn’t be the face of an issue that she’d spent two years working on. It was another instance of Clinton swallowing her pride and moving forward in a way that she hadn’t quite wanted or expected.

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“To her credit, and this gets lost sometimes, she was more than willing to play the behind-the-scenes role,’’ said Chris Jennings, a senior White House aide on health care in the Clinton administration. “She knew — or she feared — if she did it too publicly, it would be counterproductive politically and it might attract more opposition.’’

But even if the public wasn’t seeing Clinton’s role in the new health care fight, key insiders felt her presence. Just weeks after Clinton’s plan failed and after the 1994 midterm elections in which Democrats lost 54 seats in the House, a dozen top White House aides huddled in the Map Room in the basement of the White House.

“In the meeting, Hillary said, ‘Listen, we can’t pretend like the problem just disappears,’ ’’ recalled Jennings. “ ‘We obviously can’t ignore what we just went through and be in denial. But that doesn’t mean we can’t or shouldn’t work on some policy going forward.’ ’’

On the Hill, Senators Edward Kennedy of Massachusetts and Orrin Hatch of Utah were trying to build a bipartisan consensus around the idea of providing health coverage for more children.

Clinton embraced the idea quickly and pulled on the levers of power available to her to get it passed. That included pressing to get a line in a State of the Union address her husband gave supporting the legislation.

It might sound small, but among Washington insiders, it was a key signal that the administration was serious about the proposal.

Within the White House, she fended off the so-called budgeteers who wanted to raid the funds for the program. As the plan went through the House, she wanted $16 billion set aside for it and won. Later she helped get that number bumped up to $24 billion.

“The children’s health program wouldn’t be in existence today if we didn’t have Hillary pushing for it from the other end of Pennsylvania Avenue,’’ Kennedy said to the Associated Press in a 2007 interview.

The legislation was signed into law in August 1997. It now covers 8.1 million children, according to Medicaid data.

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Crushing is how Clinton’s friends described her losing the 2008 nomination to Obama. She had entered the race then — as she did this time — as the clear favorite. And then she quickly began losing ground to a charismatic but much less well known senator campaigning on a message of hope and change.

Clinton kept campaigning until all the states voted in the primary election. But by the time the South Dakota primary, one of the last, rolled around June 3, the outcome looked grim. George McGovern, the 1972 Democratic nominee, had switched his support to Obama from Clinton and was stumping the state.

The Clintons tapped Representative Jim McGovern of Massachusetts to travel with them and campaign there. “I think they sent me out there — even though there’s no relation — to confuse people,’’ McGovern recalled.

Hillary Clinton delivered a rousing speech, he said, even though it was clear to many that she’d lose the nomination and probably South Dakota, too. McGovern flew with Clinton back to New York. “Even with all this happening around her . . . she took out a book and started reading. I was so uptight and nervous,’’ he said. “She was as calm as can be.’’

But she still struggled with the decision to leave the race.

On the day of her June 6 concession speech at the Building Museum, there were two versions, according to a person familiar with the events of the day. One was the draft she read. In the other, she was fighting on. “There were people in her world telling her to take it to the convention,’’ said one person close to Clinton.

After conceding, she didn’t go straight back to the Senate but took a few weeks to be with her family. That meant missing 12 of the 13 votes the Senate held in the weeks after she conceded, including legislation designed to hold energy companies accountable for high prices, an income tax cut, and — ironically — a health care expansion bill.

At the 2008 Democratic convention in Denver, the Obama campaign had a request for Clinton. It was another chance to swallow her pride and press on: Could she interrupt the roll call vote and formally ask the delegates to declare Obama the nominee without each delegation having their say?

Clinton was torn — some of her friends and allies thought it was important to record how much support she’d gotten during the hard-fought primaries.

As the New York delegation was asked to nominate, Clinton did her duty. “Let’s declare together in one voice right here, right now, that Barack Obama is our candidate and he will be our president.’’

She rose to the moment, and preserved her prospects. Eight years later, persistence has paid off.

Annie Linskey can be reached at annie.linskey@globe.com. Follow her on Twitter @annielinskey.