The early voting, which is actual ballots that are being cast, shows that Democrats are doing very well. Many states have already started early voting, and more will open up their polls soon.
Some of these sates actually break up the ballots in a way that allows us to know how many are Democratic and how many are Republican. Here are the states that we know about so far (note that early voting is not complete in these states):
Iowa: About 46% Democrat to 38% Republicans early ballots.
Maine: Things are roughly even between Democrats and Republicans.
North Carolina: Democrats have about 44% of votes compared to 39% for the GOP.
Maryland: About 59% Democrat vs. 31% Republican.
Ohio: Democrats leading at 59% to 26% in Cuyahoga County, while Republicans lead 42% to 33% in Hamilton County. In Franklin County, things are tied.
Louisiana: Democrats leading 46.6% to 42.7%.
Nevada: In Clarke County, Democrats are leading by a substantial margin, but well behind in much smaller Washoe County.
The main exception has been in Colorado where Republicans lead by 41.8% to 36.5%.
Again, this is good news because these are votes that are cast and cannot be changed. Of course, we cannot assume that all Democratic ballots translate into votes for all the Democratic candidates. Some states like Ohio, for example, are known for Democratic swing voters.
However, historically speaking Democrats turn out in lower numbers for early voting especially during the mid-term elections. So, this is good news indeed everything else being equal.
Also, with a large number of Democrats voting early it will make things easier in getting out the vote further down the road toward election day. Smart campaigns will not bother contacting those people who have already voted. The data provides further positive evidence that the so-called "enthusiasm gap" may be exaggerated.