NBC News Data presents an analysis completed by TargetSmart showing key states and the registered affiliations of early voters.  Within the analysis Republican voters are leading Democrats in all states except Nevada.  [Note the Nevada result should not be a surprise because as we saw in the 2016 presidential campaign, there are several organized groups who coordinate bus loads of Californians into Nevada to vote in both states.]

Additionally, the underlying data must be troubling for democrats for two reasons.  First, NBC is admitting the ‘blue wave’ is in trouble; that’s not typical.  Secondly, within the NBC report they attempt to water down the result by saying that Democrats usually don’t turn out as well in votes before election day, and usually do better ‘on’ election day.  This is historically false.  Republicans usually vote much heavier on election day than democrats; and democrats have always relied upon pre-election day voting to carry them.

(Via NBC) […]  GOP-affiliated voters have surpassed Democratic-affiliated ones in early voting in Arizona, Florida, Georgia, Indiana, Montana, Tennessee and Texas, the data showed.

Only in Nevada have Democratic-affiliated voters exceeded Republican-affiliated voters so far in early voting, according to the data.
[…] The latest data suggests robust enthusiasm among early Republican voters that could put a dent in Democratic hopes for a “blue wave” in next month’s midterm elections.  (See data here)