CNN Poll: Questions about accuracy of vote counting rise as most want to vote before Election Day

And as the coronavirus pandemic enters its sixth month of changing nearly every aspect of American life, the poll also finds a majority of voters prefer to cast their ballots before Election Day, far more than have ever done so in previous presidential elections.

A majority of Americans (55%) say they don't think President Donald Trump will concede should he lose. A slightly larger majority said that in 2016 (61%), but Trump was not a sitting president then. There is near unanimity, though, that once all states have certified their votes for president, the loser should accept the results and concede (87% feel that way, up from 77% in October 2016).

A sizable minority (36%) say their confidence in the count will be diminished if a winner cannot be determined on election night because it is taking longer than usual to count, a prospect that is increasingly likely as larger shares of the public turn to by-mail ballots to cast their votes.

Among all registered voters, 34% say they prefer to vote by mail in the presidential election, 22% say they want to vote early at a polling place, and just 43% say they would prefer to vote in-person on Election Day. That represents a 10-point increase over the share who voted by mail in 2016: 24%, according to the U.S. Elections Assistance Commission.

The political divide over how voters want to cast their ballots is stark. Among supporters of the President, 66% say they prefer to vote in person on Election Day. Those voters backing former Vice President Joe Biden mostly prefer to vote by mail (53%).

Should this divide carry through the election, it could result in election returns which look wildly different from what Americans are used to seeing. Election officials sometimes count entirely one type of ballot first, and then shift to the other, meaning this year, early returns may not be representative of the full pool of votes. Differences between absentee vote and Election Day vote have not generally been as uniformly partisan in the past.

For example, two years ago in Arizona, Republican Martha McSally was ahead on election night, but Democrat Kyrsten Sinema later took the lead. Once that happened, Trump decried "corruption" and tweeted, "call for a new election?" McSally later conceded.

The poll also finds majorities of Americans are concerned that changes to the rules regarding voting meant to make it safer to cast a ballot during the coronavirus pandemic won't go far enough (64% are at least somewhat concerned about that) and that those changes will make it too easy for people to cast fraudulent ballots (59% concerned). But concern only overlaps for a small share of the public: Just 36% express concerns about both.

One comprehensive study of voter fraud, which examined more than 1 billion votes between 2000 and 2012, found a microscopic level of fraud in US elections, but determined that when fraud did occur, absentee ballot fraud was one of the more common methods.

Trump's handling of election security criticized

In recent weeks, Trump has, without evidence, questioned the legitimacy of by-mail ballots and falsely claimed that the country may never know the results of the election.

Overall, 51% of Americans say they disapprove of the way the President is handling the security of elections in the United States, 40% approve. The poll was in the field as news broke about changes to the US Postal Service which may have been politically motivated.

Experts say Trump's comments undermine public confidence in the election process and that he might be setting the stage to dispute the results if he loses.

Trump has forthrightly stated that he might not concede should Biden prevail in the count. He was repeatedly pressed in a Fox News interview in July, and refused to commit that he will accept the outcome of the election. "I have to see," Trump replied, "No, I'm not going to just say yes. I'm not going to say no, and I didn't last time either."

Trump's own supporters do largely say that the loser of the election has a responsibility to concede, as do most Biden supporters (83% among Trump supporters, 94% among Biden's voters), and despite Trump's noncommittal stance, most voters feel that their chosen candidate will follow through with a concession (68% of Trump voters say he will, 83% of Biden supporters say the former VP will). Trump backers, though, are far more confident that Biden will actually follow through and concede (51%) than Biden backers are that Trump will (16%).

Spurred by the coronavirus pandemic, states across the country, with election officials of both parties, have expanded mail-in voting in numerous ways.

The degree of change varies by state. Some states, mostly with Democratic leadership, have switched to universal voting-by-mail for November, where every registered voter will automatically receive a ballot in the mail and limited in-person voting will be offered on Election Day. Other states are mailing absentee ballot applications to all registered voters. Some have rolled back requirements that voters provide an excuse in order to get an absentee ballot or have included worries about coronavirus as a valid excuse. Some have changed the deadlines by which ballots must be received or postmarked. These changes have come rapidly, and experts have warned that voters might be confused by the new policies.

Changes to the rules around voting raise concerns for sizable shares of Americans, but exactly what voters are concerned about varies with their choice of candidate. Throughout this year's campaign, Trump has repeatedly spread false information and debunked lies about voting procedures, claiming over and over that there is massive fraud and that the election is being "rigged" against him. The poll suggests his comments are raising worries about fraud among his own supporters and diminishing the confidence of those who oppose him in the election process more generally.

Among Trump voters, 87% are concerned about it being too easy to cast fraudulent ballots, compared with just 32% of Biden backers. On the other side, Biden's voters are more concerned that it will still be too hard for eligible voters to cast ballots safely (81%) than are Trump voters (47%).

Trump supporters express less confidence in the accuracy of voting and counting this fall, 50% say they are very or somewhat confident vs. 65% among those who support Biden. But the shift since 2016 comes almost entirely on the Democratic side. Supporters of Hillary Clinton were largely confident that votes would be cast and counted accurately in 2016, 88% felt that way, while among backers of Trump, 49% were confident.

The impact of an extended count on confidence is more clearly negative among Trump's voters: 53% say not knowing the results on election night would diminish their confidence in the vote, while a plurality of Biden's supporters say it wouldn't affect their confidence (49%). The rest of Biden's voters are split over whether it would make them more (27%) or less (23%) confident in the accuracy of the result.

The CNN Poll was conducted by SSRS August 12 through 15 among a random national sample of 1,108 adults reached on landlines or cellphones by a live interviewer, including 987 registered voters. Results for the full sample have a margin of sampling error of plus or minus 3.7 percentage points. It is 4.0 points among registered voters.