As Election Day nears, both Democratic and Republican campaigns are ramping up their efforts to get out the vote. With the rise of early and absentee voting across the country, campaigns are increasingly focused on early voting as a method of securing an early lead in the race.

One way that campaigns try to accomplish this is to motivate voters to request an absentee ballot. By tracking and analyzing these requests, campaigns get an early glimpse into how well their get-out-the-vote efforts are working in the very early stages of the campaign.

The first batch of absentee ballot request data suggests that Hillary Clinton may have an early advantage, though Donald Trump appears to be better positioned in Florida, a key swing state.

The NBC News Data Analytics Lab -- using data provided by TargetSmart — analyzed absentee ballot requests in six critical battleground states – Florida, Iowa, Michigan, North Carolina, Nevada and Pennsylvania. The chart below shows the number of requests received so far.

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As of September 22, more than 2.5 million absentee ballots had been requested in Florida. This large number of requests is due in part to the rules governing the process there -- voters have the option of requesting that an absentee ballot be automatically mailed to them as soon as they are available. In other states like Pennsylvania, the rules regarding which voters are eligible to vote absentee, as well as the process for applying for a ballot, may be more strict or intensive. This means the state will have far fewer ballot requests than others.

The more informative number for campaigns is the partisanship of these ballot requestors. Given that voting is so highly partisan, and that public opinion polls regularly show that Republicans and Democrats alike support their own party’s candidate consistently, the partisan breakout of ballot requests is a good indicator of how each candidate is doing. In five of the six battleground states analyzed here, more Democrats have requested ballots so far than Republicans.

Clearly not all of these requests will turn into real votes, but one method of assessing the likelihood that they will return filled-in ballots is to see what percentage of these requestors also voted in 2012. Extensive research suggests that voting is habit forming, so a good predictor of whether a person will end up voting in the 2016 general election is whether they voted in the 2012 election.

Overall, the number of requestors this year who also voted in 2012 seems fairly high in all six battleground states. In Michigan, 91 percent of those who have submitted ballot requests so far also voted in 2012. In Iowa, 84 percent also voted in 2012.

One other measure of interest to either candidate, especially the Clinton campaign, is the age breakdown of these early ballot requestors. Recent polls have suggested that younger voters favor the Democratic candidate strongly over Trump.

As the chart below demonstrates, most of those who have submitted absentee requests so far skew much older. This is expected as historically, voters who vote absentee are older than Election Day voters.

There are notable differences in Pennsylvania and North Carolina. In Pennsylvania, a quarter of absentee applications have come from voters younger than 30. This may also explain why just 64 percent of ballot requestors in Pennsylvania have a record of voting in 2012. In North Carolina, this number is 16 percent—a higher proportion than those age 30 to 44 who have requested ballots.

This early look at ballot requests is only a slice of data, and the volume and composition of those who end up voting absentee in the 2016 election may look quite different than this first glimpse. It is this type of data, however, that are being methodologically tracked by campaigns as updates are received almost daily in the lead up to Election Day.

For methodological details, please click here.