A stack of vote-by-mail ballots sit in a box after being sorted at the San Francisco Department of Elections | Getty Images Stanford study: Mail voting doesn't benefit one party over another

OAKLAND — Mail voting does not decisively advantage either party, a new analysis finds — a conclusion that contradicts President Trump’s criticism that vote-by-mail undermines Republicans.

Coronavirus-spurred limits have intensified a push to allow more mail balloting in November, particularly after Wisconsin saw perilously crowded polling places last week.


“Many scholars and policymakers are urging the U.S. to implement a nationwide system of voting-by-mail to safeguard the electoral process” in response to the outbreak,” the authors of a new Stanford University study note.

That effort has largely been confined to Democratic elected officials, with President Donald Trump directing Republicans to “fight very hard” against a system that “doesn’t work out well for Republicans" and House Minority Leader Kevin McCarthy decrying Speaker Nancy Pelosi’s move to fund more mail balloting.

But the Stanford study found that in three states that have instituted widespread mail voting — Washington, Utah and California — turnout rose slightly but there was “no discernible effect on party vote shares or the partisan share of the electorate.”

“The expansion of vote-by-mail does not appear to tilt turnout towards the Democratic party, nor does it appear to affect election outcomes meaningfully,” the authors wrote, adding their findings “support the conventional wisdom of election administration experts and contradict many popular claims in the media.”