The former housing secretary Julián Castro on Tuesday became the 10th Democratic presidential candidate to qualify for the next round of debates, after a new national poll showed him earning 2 percent support.
The poll, conducted for CNN by SSRS, a research firm, was the fourth qualifying poll to show Mr. Castro having cleared that hurdle. He had already met the other qualifying standard set by the Democratic National Committee by receiving donations from more than 130,000 people.
In qualifying for the third set of debates, Mr. Castro joins nine other candidates who have also done so: former Vice President Joseph R. Biden Jr.; Senator Cory Booker of New Jersey; Mayor Pete Buttigieg of South Bend, Ind.; Senator Kamala Harris of California; Senator Amy Klobuchar of Minnesota; former Representative Beto O’Rourke of Texas; Senator Bernie Sanders of Vermont; Senator Elizabeth Warren of Massachusetts; and the entrepreneur Andrew Yang.
“With two standout debate performances, Secretary Castro has been building momentum for his candidacy,” his campaign manager, Maya Rupert, said in a statement. “He has never wanted to be a ‘flash in the pan’ candidate, but rather has continued to build support and momentum by leading the field on critical issues and showing voters every day why he’s the best candidate to go toe-to-toe with Donald Trump.”
Candidates are required to both have 130,000 unique donors and register at least 2 percent support in four polls in order to make the cut for the next debates, scheduled for Sept. 12 and 13 in Houston. They have until Aug. 28 to reach those benchmarks.
All of the candidates who qualify for the September debates will also make the cut for the following round of debates, in October.
Mr. Castro, who is also a former mayor of San Antonio, released a new ad last week in which he sharply criticized President Trump and accused him of inspiring the mass shooting in El Paso this month that left 22 people dead. The ad aired on Fox News in Bedminster, N.J., while Mr. Trump was vacationing there, and shortly before the CNN poll was conducted.
The new CNN poll also helped Representative Tulsi Gabbard of Hawaii inch closer to debate qualification. Like Mr. Castro, she earned 2 percent support in the poll, leaving her just two surveys short of meeting the D.N.C.’s standard; she has already surpassed the donor threshold. Ms. Gabbard left the trail last week in order to fulfill her obligations with the National Guard, and is scheduled to resume campaign activities this Sunday.
Tom Steyer, the former hedge fund investor turned impeachment activist, needs only one more qualifying poll to make the cut for the debates, having already met the donor standard. When he entered the race in July, his team said he planned to spend at least $100 million on the race. In the weeks since, he has spent millions of dollars on internet and television ads that have helped him attract donors. He received 1 percent support in Tuesday’s CNN poll.
Senator Kirsten Gillibrand of New York, who received less than 1 percent support in Tuesday’s poll, is the only other candidate still shy of making the cut who has earned 2 percent support in any qualifying poll. She has amassed more than 100,000 individual donors.
No other lower-tier candidate in the 23-person field is particularly close to making the debate stage. Gov. Jay Inslee of Washington announced Monday that he had crossed the 130,000 donor threshold, but he needs to earn 2 percent support in four polls in the next week to qualify.
And on Tuesday, the self-help author Marianne Williamson announced that she had also met the donor requirement, but like Mr. Inslee, she needs to earn 2 percent in four qualifying polls.
Mr. Castro, who has focused his campaign around issues like education and immigration, was buoyed by a strong performance in the first debate. He confronted Mr. O’Rourke over his immigration policy and argued for decriminalizing border crossings — a stance many of his rivals have since adopted.
Mr. Castro saw an uptick in fund-raising after the first debate, but his performance in polling has continued to hover in the low single digits.
The CNN poll released Tuesday had Mr. Biden in the lead with 29 percent of Democrats or Democratic-leaning voters selecting him as their first choice for the nomination. Mr. Sanders finished next with 15 percent support, essentially tied with Ms. Warren, who had 14 percent.
Mr. Buttigieg and Ms. Harris came in next, both with 5 percent support. Ms. Harris had earned 17 percent support when the CNN survey was last conducted in late June, immediately following a standout performance in the first debate.
The poll was conducted Aug. 15 to 18 and surveyed 402 Democrats and Democratic-leaning independents who are registered to vote. It had a margin of sampling error of plus or minus 6 percentage points.