As of Thursday morning, a total of 17,360,907 ballots have been cast throughout 42 reporting states, in an election expected to be conducted largely by mail due to COVID-19.

The U.S. Election Project, run by University of Florida professor Michael McDonald, found that the majority of the ballots cast ahead of the Nov. 3 election date in the 15 states that report party registration data thus far have been from Democratic voters — 4.3 million have been returned, compared to the Republicans’ 1.8 million, though those numbers only apply to the small percentage of states reporting party registration information.

Those 15 states — California, Colorado, Florida, Iowa, Kansas, Kentucky, Maryland, Maine, North Carolina, Nebraska, New Jersey, Nevada, Oklahoma, Pennsylvania and South Dakota — showed that 10 million more Democrats requested mail-in ballots (23,635,124) than Republicans (13,904,914). An additional 15 million voters without a party affiliation requested ballots in those states as well.

The small proportion of Republicans voting by mail is unsurprising for two reasons.

According to an analysis by Pew Research Center released in June, 34% of registered voters identify as independents, 33% as Democrats and 29% as Republicans. When the party leanings of the independents are factored in, 49% of registered voters identify as Democrats or lean Democratic, and 44% identify Republican or lean Republican.

President Donald Trump has strongly discouraged his Republican followers to cast their votes in-person to make them count, citing false claims of mail-in ballot fraud.