With Election Day less than a week away, more than 42 million out of the 92 million mail ballots requested by voters nationally had not yet been returned as of Wednesday afternoon, according to data from the U.S. Elections Project, a nonpartisan site tracking early voting.

In the 20 states where party affiliation data was available, more than 11 million of the outstanding ballots had been requested by Democrats, nearly 8 million by Republicans and about 10 million by unaffiliated voters, according to the Elections Project.

Tuesday marked the last day that postal and election administration experts said ballots could be mailed to ensure delivery in time for Election Day, based on national first-class mail service.

The passing of the informal deadline set off a flurry of advisories from election officials and posts on social media encouraging voters who had yet to postmark their ballots to instead drop them off at voting centers — or consider voting in person.