About six in 10 registered voters nationwide say they want to cast their ballots before Election Day, a significant departure from previous years that will force the candidates to reshape how they campaign in the election season’s final weeks, according to a Washington Post-University of Maryland poll conducted by Ipsos.

Fear of the coronavirus and doubts about the reliability of mail voting after months of attacks from President Trump are weighing heavily on Americans as they decide how to safely ensure their vote will be counted in this fall’s presidential election, according to the survey. In 2016, about 4 in 10 ballots were cast early.

The likely surge in early voting and mail ballots will test election systems nationwide, many of which are ill-prepared to contend with an unprecedented volume of early votes or help voters who are struggling to learn the rules around mail ballots.