I quickly saw an article, but didn't read it, where even though most consider many of the early voters to be majority Democrats, the Republicans are pointing to an increase in registered R voters in three key swing states and who have not voted yet. I have seen that stat a few weeks ago as well. Thus, the Republicans are holding out hope on that.
I've read the same thing, but it comes down to selective counting. There were lots of people who voted in 2018 for the first time, who will likely vote in 2020, and are not counted in these "new registration" tallies.