I think the problem might not be so much the democrats as it is the news media as a whole.
Granted, Trump supporters will exist in their own little information bubble, watching their Fox news and swallowing everything Trump says. They are largely unreachable. But, they don't make up enough of the electorate to guarantee a win.
Part of the problem in the 2016 election is the inability of the news media to call out Trump (at least not properly). In the interest of appearing unbiased, they would broadcast many of his lies unfiltered (and when they did point out that he was lying, it was often done just as some after-discussion.) So anyone who was sitting on the fence might have ended up voting Republican (or people leaning democrat might have decided to stay home election day).
If the media decides "lets address Trump's lies at the time he is making them", much of his power goes away.