The results suggest that warnings about ballot-counting delays from election administrators and voting rights advocates are breaking through to the broader public. The coronavirus pandemic is producing a sharp uptick in voting by mail — many times the previous mail voting rates in some states, according to polling and ballot request data. And counting mail ballots can be a more time-consuming process than counting Election Day votes cast at a polling place.

A POLITICO analysis of mail ballot processing rules in 13 swing states found that three Great Lakes swing states — Pennsylvania, Michigan and Wisconsin — don’t allow for ballots to be processed or tallied before Election Day. Experts warn that those state laws simply don’t allow enough time to fully tally the expected glut of mail ballots in those states on the night of Nov. 3.

Michigan’s Republican-controlled legislature recently passed a bill, which awaits Democratic Gov. Gretchen Whitmer’s signature, that would allow some local clerks to start processing ballots on the day before Election Day. Cross-party talks over a similar measure in Pennsylvania appear to have stalled, and observers in Wisconsin are not expecting any last-minute changes that would give clerks more time to process ballots.

Election experts also warn that, because of the lag processing mail ballots, results released on election night in some critical states may not be reflective of the final results once every vote is tallied. Significantly more Democrats are expected to vote via the mail than Republicans, while Republicans favor in-person voting, according to polls. This imbalance has led to fears that Trump could declare victory based on partial returns that aren’t definitive.

Trump has already been sowing distrust about the results of the election, saying that results should be final on the night of the election and repeatedly disparaging mail-in voting, which has been widely used in many states without significant problems, as ripe for fraud.

A majority of voters in the POLITICO/Morning Consult poll — 53 percent — said they were either very or somewhat concerned that Trump would prematurely declare victory for the election. One-third of respondents expressed the same concerns about Biden.

The poll also revealed fairly widespread anxiety about the election, with majorities saying they were concerned about everything from vote tampering to technical glitches.

The POLITICO/Morning Consult poll was conducted Sept. 25 to Sept. 27, surveying 1,986 registered voters. The margin of error is plus or minus 2 percentage points.

Morning Consult is a global data intelligence company, delivering insights on what people think in real time by surveying tens of thousands across the globe every single day.More details on the poll and its methodology can be found in these two documents: Toplines | Crosstabs