Castro received a boost from Rep. Alexandria Ocasio-Cortez, who is supporting Bernie Sanders for president but still retweeted Castro's fundraising appeal to her online following, calling him “a powerful presence” in the primary who “consistently uses his platform to uplift & center issues that are wrongly marginalized, like homelessness+police violence.”

The Castro campaign held a call-a-thon Wednesday and said it brought in more than $100,000 that day. On Thursday night, senior aides and actress Justina Machado held a conference call with supporters. (Castro himself was trick-or-treating with his family.)

Julián Castro

“I personally really believe that we can’t afford to lose Secretary Castro’s voice in this race,” said Machado, who told Castro supporters she was still undecided in the primary herself. “I mean, I don’t want to see the only Latino candidate walk off that stage, and I hope that a lot of you feel the same way that I do.”

Castro’s fundraising strategy mirrored New Jersey Sen. Cory Booker’s September gambit — and its success. Booker’s campaign had told supporters that it would have to shut down unless it raised $1.7 million in the final 10 days of that month, and it exceeded the goal.

Castro’s campaign believes the fundraising surge will help the former Housing and Urban Development secretary and San Antonio mayor qualify for the November and December debates. Castro has met the 165,000-donor threshold for November and announced Wednesday that he was only 20,000 shy of December’s 200,000-donor threshold.

But he has not met any of the polling requirements in a single Democratic National Committee-approved survey. To qualify this month, candidates must reach 3 percent in four polls or 5 percent in two early-state polls. Castro has registered at 1 percent or less in all but one poll, a national Quinnipiac survey in September in which he hit 2 percent.

Castro has until Nov. 13 to qualify for the Nov. 20 debate. The standards are even higher to make December’s stage: Candidates must reach 4 percent in four polls or 6 percent in two early-state polls. But Castro has until Dec. 12 to qualify for the debate on Dec. 19.

It’s unclear whether Castro would end his campaign if he fails to qualify for the November debate. Rupert, his campaign manager, previously said, “We do not see a path to victory that doesn’t include making the November debate stage.” But for now, at least, Castro is here to stay.

He will be in Iowa on Friday through Monday to tour a long-term housing facility and discuss affordable housing, deliver remarks at the Liberty and Justice Celebration and participate in a town hall hosted by the NAACP of Des Moines.

“We’re not going anywhere — Julián will keep being a voice for the voiceless, and a champion for the Americans who have been left behind,” Rupert said in a statement Friday. “We will keep lifting up important issues others choose to ignore, and demonstrating by example why Secretary Castro is the best candidate to take on Donald Trump.”