Ariel Malka and Yphtach Lelkes for The Monkey Cage:

The survey interviewed a sample of 1,325 Americans from June 5 through 20. Respondents were recruited from the Qualtrics online panel who had previously reported identifying with or leaning toward one of the two major parties. We focus on the 650 respondents who identify with or lean toward the Republican Party. The sample has been weighted to match the population in terms of sex, age, race and education.

After a series of initial questions, respondents were asked whether Trump won the popular vote, whether millions of illegal immigrants voted, and how often voter fraud occurs. These questions evoke arguments frequently made by Trump and others about the integrity of the 2016 election.

Then the survey asked two questions about postponing the 2020 election.

• If Donald Trump were to say that the 2020 presidential election should be postponed until the country can make sure that only eligible American citizens can vote, would you support or oppose postponing the election?

• What if both Donald Trump and Republicans in Congress were to say that the 2020 presidential election should be postponed until the country can make sure that only eligible American citizens can vote? Would you support or oppose postponing the election?

Roughly half of Republicans believe Trump won the popular vote — and would support postponing the 2020 election.

Nearly half of Republicans (47 percent) believe that Trump won the popular vote, which is similar to this finding. Larger fractions believe that millions of illegal immigrants voted (68 percent) and that voter fraud happens somewhat or very often (73 percent). Again, this is similar to previous polls.

Moreover, 52 percent said that they would support postponing the 2020 election, and 56 percent said they would do so if both Trump and Republicans in Congress were behind this.