Interviews were conducted in both English and Spanish.
As is done routinely in surveys, results were weighted, or adjusted, to ensure that responses accurately reflect the population's makeup by factors such as age, sex, region and race.
No more than one time in 20 should chance variations in the sample cause the results to vary by more than plus or minus 3.1 percentage points from the answers that would be obtained if all people in the U.S. were polled. The margin of sampling error is plus or minus 4.5 percentage points for Democrats and 5.2 percentage points for Republicans.
There are other sources of potential error in polls, including the wording and order of questions.
The questions and results for this poll are available at http://www.ap-ipsosresults.com.