Reagan democrats

I think of myself as a reasonably informed citizen but I am having difficulty following the news regarding the so called Reagan Democrats. These people, sometimes referred to as blue collar voters, are credited with helping Reagan, Bill Clinton, Obama and now Trump get elected. Apparently some portion of this group is considered bigoted but no one is sure how many fall into that category. If this is the case and this group is instrumental in winning the presidency then candidates will have to take the good with the bad. The Democratic Party is now setting up plans to win this group back. Maybe it is necessary to take in some undesirables in order to win.