Democrats have been on a steady decline for the last 30-40 years... If it had not been for watergate giving them a boost, their decline would be even further along...
Fact is, the party is out of touch, out of sync out of ideas... and is no longer a serious contender at the national level... Provided the Republicans don't do something stupid they will have the majority for a long time to come.
The democrats need to fundamentally change their party to ever have a chance at majority again.... they must reject the far left and radical groups that they now are wholey owned by if they ever expect to be a force at the national level again... and that's not going to happen anytime soon.
and why they can't is:
"The moment the Democrats articulate an agenda, their already fragile coalition will atomize."