Some ninety-nine-million ballots have already been cast in the 2020 presidential election – even before the polls open across the US.
Millions of additional mail-in ballots are expected to be received during Election Day, and in 13 states and the District of Columbia, for several days after the election, including in battleground states like Ohio, Iowa, and Pennsylvania.
Of the nearly 99 million votes already received, 35.7 million were cast in person, with 63.1 million cast via as absentee or other mail-in ballots.
There are still more than 29 million mail in ballots outstanding, which were sent to voters but have yet to be returned.
Compared to the more than 138 million votes cast in 2016, the early vote in this year’s election is equivalent to 71.7% of the total vote four years ago.
Experts predict that some 150 million voters will take part in this year’s election, pushing the turnout level of eligible voters from 60% in 2016 to around 65%.
Traditionally, Democrats have benefited from high turnout, given that low-frequency voters tend to be disproportionately Democrat.
Since early voting began, Democrats have touted high turnout levels among first-time and low-frequency voters as a positive sign for Joe Biden’s campaign.
Thus far, Democrats have held a wide lead in turnout, due in part to the strong preference this year among Democratic voters for mail-in voting over in-person voting.
Republican voters, on the other hand, have preferred in-person voting, even among early voters, and with a majority of Republicans planning to turnout on Election Day, rather than cast their ballots early.
For Republicans, a Trump win hinges heavily on high Election Day-turnout among Republican voters and independents breaking for Trump to overcome the lead held by Democrats in the early vote.
The GOP’s ability to turnout Election Day voters in high enough numbers to win could depend at least in part on the weather, with studies showing mild, pleasant weather maximizing turnout, and rainy or cold weather reducing the number of voters willing to show up to polling stations.
In some states, including the battleground state of Minnesota, polling stations are being shuttered this year in precincts with few registered voters, due to the coronavirus pandemic.
While in-person voting will still be available at election offices, the closure of polling stations could make it more difficult for some rural voters to vote in person on Election Day.
But just how strong of a turnout do Republicans need to overcome the Democratic early vote advantage?
Measuring the Democratic lead in turnout is difficult, given that most states do not list data on the partisan makeup of early voting.
Of the 99 million votes cast, just 48 million are from states which release information on voter registration and party affiliation.
Of those 48 million votes, 45.1% were cast by registered Democrats, versus just 30.5% from registered Republicans, 23.7% by independents, and 0.7% by members of third parties.
Those figures are misleading, however, both because of the large number of states which don’t report the partisan breakdown of the early vote, but also because of the differences in early voting across states.
In Florida, for example, which allows both mail-in and in-person early voting, Democrats hold a very narrow lead of 1.2 points, 39.1% to 37.9%.
But in Pennsylvania, which permits only mail-in early voting, the numbers skew heavily towards registered Democrats, who currently lead registered Republicans 66.1% to 23.0%.
While nearly nine million votes have already been received in Florida, less than 2.5 million have been cast in Pennsylvania.
Data analysis companies try to use demographic data to estimate the partisan breakdown of the vote – including in states which do not report party affiliation from early voting.
A Democratic firm, Target Smart, estimates that out of the 87.7 million votes it has calculated for thus far, 47.9% are from Democrats and 41.8% are from Republicans.
Target Smart also breaks down the estimate by state, assigning Democratic or Republican-leaning unaffiliated voters to their likely parties.
In Florida, the Democratic lead is erased in the Target Smart estimate, with Republicans leading in the early vote 46.9% to 46.0%.
The model also estimates Republicans lead in the early vote in Ohio by six points, 46.6% to 40.3%.
In Michigan and Wisconsin, Democrats hold modest leads; 42.3% to 38.6% in Michigan, 39.3% to 37.8% in Wisconsin.
In Arizona, the early vote is nearly evenly divided, with Democrats narrowly leading Republicans in terms of turnout by registration, with 37.4% to 37.0%. The Target Smart estimate, however, shifts the race slightly in the Republicans’ favor, to 46.9% for Republicans and Republican-leaning voters, compared to 46.5% for Democrats and Democrat-leaners.