Elizabeth Bryan, a 25-year-old social worker in New York City, had forgotten that Julián Castro, a former Housing and Urban Development secretary, was running for president. But she was so taken by his performance in the Democratic debate that she paused from watching to donate to his campaign.

“I was so impressed and grateful that he brought those things up,” Bryan said, referring to immigration and reproductive health, which she said are the two issues she cares most about.

Castro was buoyed by donations from viewers like Bryan. The day after the debate, his campaign said it raised three times as much as it had collected on its previous best fundraising day.

The size of the Democratic primary field — 25 candidates — and the convenience of donating online have changed the way primary voters watch debates, bringing a level of viewer participation that was unheard of in past elections.

Those two factors also have changed the way people donate money — and to whom. Democrats this year are giving not only to help their preferred candidates, but also to offer a small token of appreciation for a clever policy idea for someone else, or to keep an underdog in the game.

Welcome to the 2020 primaries, an era of crowdfunded presidential debates.

Campaign donations and debates have become intermingled this year, with the Democratic National Committee for the first time requiring that candidates reach a certain number of donors to qualify for primary debates. That has created an intense focus on fundraising, with candidates asking supporters for money specifically to help them qualify for the widely watched forums.

More than 100 debate viewers nationwide responded to a call-out by The Washington Post on Instagram, asking them about the moments that resonated with them and drove them to give money. The Post interviewed dozens of the respondents, mainly through Instagram direct messages but also by phone.

“I’ll continue watching the debates. They’ll be the primary way I shape my decision for my primary vote,” said Sebastian Bernal, 28, a student living in the District.

Bernal, who had donated to Pete Buttigieg, the mayor of South Bend, Ind., gave money to Castro’s campaign after the debate, saying: “I’m Latino; it felt good seeing a Latino on the stage.”

Technology has made it easier than ever for donors to give in real time and for candidates to capi­tal­ize on the emotional moments they generate onstage. Viewers can pause their live streams, send money with one click on their mobile phones and resume watching.

Even the offbeat performance of self-help guru Marianne Williamson, who spoke a total of five minutes during the forum, spurred donations — including from Republicans who made tongue-in-cheek solicitations to keep her in the debates.

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The intense focus on fundraising for and around these exchanges has led to big sums in online donations, according to figures provided by ActBlue, a fundraising platform used by all the Democratic presidential hopefuls.

In the last seven days of June, which included the two-night Democratic debate, 1.1 million unique donors gave money to Democratic candidates and organizations, according to ActBlue. In comparison, 4.9 million unique donors gave money via ActBlue during the entire two-year 2018 election cycle, ActBlue said.

As campaigns made a push for donations before the second quarter fundraising deadline Sunday, ActBlue said more than 390,000 contributions were made that day, the largest number given on its platform.

Sen. Kamala D. Harris (Calif.) announced that her campaign had its best online fundraising day in the 24 hours after the debate, bringing in more than $2 million from 63,277 people. Of those donors, 58 percent were new contributors, the campaign said.

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Two of those donors were Olivia Koenig, a 19-year-old student in Georgia, and her father, who watched the debate together. Koenig was already drawn to Harris before the forum, but was open to supporting other candidates, including Buttigieg.

But Harris’s story about attending an integrated elementary school and her confrontation of former vice president Joe Biden over his past position on busing — one of the biggest moments of the debate — drove Koenig and her father to donate.

“The moment where Senator Harris shared her personal story with busing into school as a child, standing up for her experience as a black woman in America, made me emotional and also helped me relate to her more on a personal level,” Koenig said.

Almost immediately after the exchange with Biden, Harris’s campaign tweeted a photo of Harris as a child, with a part of her quote from the debate: “That little girl was me.” The next day, her campaign was selling T-shirts carrying the photo.

Jill Bakas, 32, an engineer from Massachusetts, bought a T-shirt for herself and her wife.

“She used her personal experiences and yet made it personal for every American,” Bakas said of Harris. “I felt her pain and emotion and it truly resonated with me when she talked busing and faced down Biden on segregation.”

‘It’s the metric, 100 percent.’ Democratic presidential hopefuls increasingly see small-dollar donations as a sign of viability.

For others, it wasn’t a specific moment that drove them to donate, but rather the contrasts that a particular candidate showed above the rest. Ann McCormick, 31, a fifth-grade teacher from Maryland, said Harris and Sen. Elizabeth Warren (Mass.) — who appeared on different nights — stood out as confident and prepared compared to the rest, and made a donation to show support for their performances.

“They have plans and ideas, and didn’t seem desperate to speak over others,” McCormick said. “I want to show support and admiration with my donation so close to the debates.”

Warren’s campaign declined to provide figures on its debate fundraising.

The focus on fundraising for the debates is likely to increase as the primary season unfolds. The DNC plans to raise the donor threshold for future forums.

Jenny Martinez Garcia, 21, a nursing student who lives in San Jose, is supporting and has donated to Buttigieg. But she also contributed to Castro and businessman Andrew Yang after watching the debate.

She gave to Yang’s campaign because she thought his comments about automation and economic frustrations of factory workers showed that he “has solutions to the problems that got Donald Trump elected in the first place. . . . I made a donation to Julián Castro’s campaign because I would like to see him onstage for the other debates.”

About 24 hours after stepping off his first debate stage, Yang announced on Twitter that he had cleared the number of donors required to reach the September debate: “Donor #130,000 is Joshua Evans from Havertown, Pennsylvania! Thank you Joshua and thank you #YangGang! Onwards to 2020!”