Yes, Sanders is a great example. The guy that the DNC literally had to put their finger on the scale to overcome. The guy that polled better than Trump in red states.
I have lived all over the country: The coasts, the middle, the south. I know plenty of people in red states that don't like Trump, but don't see the Democrats putting out a candidate that they like. Maybe if the Democrats tried to differentiate themselves from Trump, instead of chasing his policies, they'd do better.