Kerri Harris jumped into Delaware’s U.S. Senate primary in February, offering Democrats an alternative to Sen. Thomas R. Carper. There didn’t seem to be many takers. The 38-year-old Harris, a veteran and social worker, raised just $17,138 for her campaign, compared with Carper’s $2.3 million. Even a friendly profile writer suggested that Harris was “tilting at a particularly formidable windmill.”

Then in June, Harris had an idea — what if she helped Alexandria Ocasio-Cortez, a fellow insurgent candidate challenging Rep. Joseph Crowley (D-N.Y.)? Her primary was on June 26; Harris’s isn’t until September. On June 25, Harris and five members of her campaign team piled into a Prius and a Toyota Highlander and drove the four hours to New York, ready to get out the vote.

“The guys in the Highlander drove past Sen. Carper,” she said. “He was jogging.”

Harris’s road trip paid off. In just six days since Ocasio-Cortez’s victory, Harris has netted more than $15,000 from 429 donors from 41 states and the District — almost as much as she had raised since the start of her campaign. She gained hundreds of social media followers, too, after an endorsement from Ocasio-Cortez was retweeted more than 10,000 times.

“The guys who didn’t think we could win before are now believers,” Harris said. “They know that we’re energized and our voices are going to be heard. Inside the campaign, we all had that mentality before, but now we’re showing this is real, this is how change happens.”

Ocasio-Cortez, whose upset victory made her an instant political star, has spent the days since then alternating between media interviews and endorsements of like-minded candidates. She’d always intended to turn her campaign staff over to other New York insurgents; many “AOC” campaign veterans are now focused on defeating Democratic state senators who caucused with Republicans.

In races across the country, Ocasio-Cortez’s endorsement has been an incredible signal-booster, drawing fresh attention to candidates who had been struggling for it. She has backed Brent Welder, a candidate for Congress in Kansas; Kaniela Ing, a candidate in Hawaii; Chardo Richardson, a candidate in Florida; and Abdul El-Sayed, a candidate for governor of Michigan who had sometimes gotten lost in a three-way race.

All of the insurgent candidates are also endorsed by Justice Democrats, a group created in January 2017 with the express purpose of replacing “corporate Democrats” — politicians seen as overly programmed by their donors — with “progressives” in the mold of Sen. Bernie Sanders (I-Vt.). Justice Democrats would endorse universal Medicare, a $15 minimum wage and free tuition at public universities, all while turning down any corporate PAC money. Cenk Uygur, co-founder of the Young Turks, co-founded Justice Democrats. He later left the leadership but used his YouTube-based news show to promote the candidates.

Until Tuesday, the Justice Democrats experiment did not have a major win to point to. It had been mostly successful in races in which the Democratic Party’s establishment did not see a reason to compete, including in some deep-red districts in Texas. Last year, a similar primary-bad-Democrats effort, #AllOfUs, folded into Justice Democrats.

Ocasio-Cortez’s victory changed those dynamics. According to Corbin Trent, a Justice Democrats co-founder who spent seven weeks working full-time for Ocasio-Cortez, this was the dream all along — one breakthrough candidate who demonstrates that incumbents are beatable.

“We talked about going all-in for AOC a year ago,” Trent said. “She embodied so much of what we wanted to accomplish. Not everyone is happy about how the attention moved toward her — not toward them — but the ones who realize what’s happening, they’re absolutely excited. They know this is good for their races.”

Since June 26, Trent said, fundraising for Justice Democrats has doubled, even though the group is not always mentioned in stories about Ocasio-Cortez. “I get that ‘socialist’ sells more newspapers than ‘Justice Democrats,’ ” he said.

At a glance, many of the Justice Democrats have tougher primaries than Ocasio-Cortez. Carper, who at 71 has been winning elections in Delaware for most of his life, has a more favorable and moderate-leaning primary electorate than Crowley did. El-Sayed trails two other candidates in Michigan; Ing is near the back of the pack in his Hawaii race. (Ing, like Ocasio-Cortez, is a member of Democratic Socialists of America.) But Ocasio-Cortez’s win is getting them a second look from the news media, which does not want to miss another upset, and donors, who are eager to rally behind another “impossible” cause.