There is no evidence that mail-in voting privileges one party
There is no evidence to suggest that mail-in voting favors one political party. A study published by Stanford University states that both political parties benefit from the surge in voter turnout that mail-in elections bring. Studies analyzing the results of all-mail elections in Colorado in 2014 and Utah in 2016  saw slight partisan advantages in each state. But the advantages were marginal, and turnout increased in each election, particularly among voters who were least likely to vote. Oregon and Washington, two states that pioneered mail-in ballots, often are among the highest-turnout states in the country. Media and the general public assume that Democrats support mail-in ballots while Republicans (and President Donald Trump) oppose mail-in ballots. Yet, some Democrats have been hesitant to embrace a prospective all mail-in system, citing a study that shows Black and Latino voters—who often lean Democrat—are less likely than their white counterparts to embrace the option. Conversely, some Republicans in Florida are eager to adopt mail-in voting, hoping that it will help the states large number of retirees participate in elections. Both Democrats and Republicans support and oppose mail-in ballots to better serve their interests, so mail-in voting does not privilege one party over the other.
Mail-in voting benefits Republicans, contrary to what President Donald Trump might say. Mail-in voting could help Republicans by encouraging retirees to vote, who often skew Republican. Mail-in voting also largely disadvantages minority voters. African-American voters, for example, traditionally rely on in-person voting and are more likely to have changed their address recently. Also, 18-21-year-old voters—who are infrequent yet Democratic voters—had their ballots rejected nine times more than their elderly counterparts in Florida's 2018 election. In the same election, minorities were twice as likely to have their ballots rejected as their white counterparts.
Rejecting the premises