The Democrats are too tied to social issues.
This has a certain level of truth.......but they aren't the only ones. In the GOP, it's the pocket of religious right conservatives primarily who are preoccupied with this. The GOP has the problem of "we need their votes and can't win without them, but we're not going to do anything for them." Kinda like the Democrats have become with the black vote.
They are doomed as long as white Americans are in the majority. and as long as a majority of americans are against Abortion and gay rights.
At no time in any polling has the majority of Americans been pro-life. The politics of abortion are far more complicated than the bumper sticker mentality of the parties and press. Since 1973, it's not really changed at all. Around 58% of people want abortion legal while around 53% consider it murder. (yes, there is a small group of people who consider it murder and still want it legal).
As far as gay rights....my own views as an evangelical on this are somewhat nuanced but let's just cut right down to the core: Americans on the whole simply don't want to get down and dirty and involved in that, but I'll guarantee you most folks basically look at it pragmatically: "Well, who exactly is gay marriage hurting?" At least with abortion one can make the argument of harm to a person/potential person (folks, I'm musing and I'm not going to get involved in the nuances of that debate given that in over 30 years I've never once seen an argument on that subject change one single mind).
That simply cannot be done with gay marriage.
National races basically come down to TWO subjects: economics and national security. Even health care is really a (primarily) economic issue.
It is, however, long past time the press quit pretending that gun control, abortion, gay marriage/rights, and the environment rank overly highly in the minds of most Americans. Those are volatile, red button issues, but they are way down the list of "concerns most people want addressed by Washington." School prayer is another one. (Ok, education ranks up there, too, but in large part because it, too, has economics tied to it).
Since 1980, there have been ten Presidential races featuring a professing pro-life candidate (GOP) against a professing pro-choice candidate (Dem). The scorecard reads 6-4 in favor of the GOP, although we could call it 4-6 on the basis of the popular vote. The GOP won three ground-shaking landslides with pro-life candidates (and for the record, Trump's pro-life stance is nothing more than saying what the GOP base wants to hear; I've long said this guy has probably paid for abortions out of his pocket).
If the NATION was as obsessed with this particular issue as the press likes to pretend and everyone voted the abortion issue based on polling, the last GOP President would have been Gerald Ford, who wasn't even elected. The truth is - as Zell Miller said in 1991 - when Mom and Dad (or in this day, dad and dad) sit down at night, they aren't worrying about whether school prayer should be voluntary or whether abortion should be legal at 0, 3, or 6 months or whether gays should be able to marry or serve in the military.......they're worried about where they're going to get money for college, how they're going to pay their bills, whether their kid is going to get drafted (admittedly not a worry at this point), whether they'll actually have a nation.
Those social issues, left or right, are rightly called (Mandy Grunwald used this term) "luxury issues." If your 401K is doing great and you have money in the bank then you have plenty of time to worry about whether or not abortion should be legal.