MIAMI — Sen. Elizabeth Warren, D-Mass., was the clear winner of Wednesday night's debate among members of the progressive group Indivisible, according to the results of its flash poll.

Indivisible sent text messages to thousands of its members across the country shortly after the conclusion of the first night of the first 2020 Democratic presidential primary debate to ask which candidate "impressed" most. They received responses from 6,497 people in all 50 states.

The survey is not scientific, but offers a window into the views of the Democratic Party's progressive base that viewed the debate, hosted by NBC. Indivisible was founded after President Donald Trump's election as part of the so-called resistance movement and quickly grew into a force on the left.

Warren, the biggest name on the stage Wednesday and a longtime favorite of progressives, was the pick of 56 percent of the respondents.

In a distant — but surprisingly strong — second place was former Housing Secretary Julián Castro, who was selected by 15 percent of the respondents. Castro, the only Latino in the race, has been a minor player in the primary so far, but had what was generally regarded as a strong performance in the debate.

Just behind him was Sen. Cory Booker, D-N.J., at 10 percent, followed by Sen. Amy Klobuchar, D-Minn., at 6 percent. New York City Mayor Bill de Blasio, Rep. Tulsi Gabbard, D-Hawaii, and Washington Gov. Jay Inslee came next, tied at 3 percent.

Former Texas Rep. Beto O'Rourke didn't fare well in the survey, picked by just 2 percent of the respondents, but still finished ahead of Rep. Tim Ryan, D-Ohio, who received 1 percent support and former Maryland Rep. John Delany, D-Md., a moderate, was picked by 0 percent of the respondents.

"I think it's a big win for Warren and Castro, especially when you consider Castro was coming into this debate with not very high name, ID or standing in the polls," María Urbina, Indivisible's national political director, said.

Urbina said Warren did a good job solidifying her position among progressives while Castro succeeded in getting noticed. She said it shows that the primary is far from settled and that the party's liberal base wants to learn more about all the candidates and hear them communicate with "courage and clarity."

The group will conduct another flash poll after Thursday night's debate, which features a new slate of 10 candidates including former Vice President Joe Biden and Sen. Bernie Sanders, I-Vt. NBC News will have those results.