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If you’re interested in their methodology, they’re named at the bottom of the linked AP article, and they have a page that answers that exact question.
“The poll of 1,165 adults was conducted Aug. 10-14 using a sample drawn from NORC’s probability-based AmeriSpeak Panel, which is designed to be representative of the U.S. population. The margin of sampling error for all respondents is plus or minus 3.8 percentage points.”
So it doesn’t say how. I have this idea that they call people. I also have this idea that no one in certain age groups and demographics answers their phone, so are underrepresented.
And if you Google their name, they have a page that gives a summary of how they conduct their polls.