While five states conduct their elections entirely by mail and 29 states don’t require an excuse to vote absentee, not all states are equipped to process the huge uptick in ballots as quickly. New York City election officials are still in the process of counting ballots from the June 23 primary, which took place three weeks ago.

One major issue is that many states aren’t allowed to even begin opening returned ballots before Election Day on November 3, putting extra burdens on Election Day workers.

In Wisconsin, Michigan, and Pennsylvania — all states that flipped from Democratic to Republican in 2016 by thin margins, fueling Donald Trump’s win — officials are urging their state legislatures to pass bills that would allow them to open and process ballots before Election Day. Without it, they say campaigns could be waiting awhile for results.