It's very odd to suggest that the Democratic party went off the left end of the Earth, since in most ways the current Democratic party is more conservative than prior generations of Democrats (e.g., more conservative than New Deal and Great Society era Democrats), and in nearly all ways the Democratic party is more conservative than the center-left parties of nearly every other major wealthy nation (e.g., more conservative than the European Social Democrats).
Look, for example, at the tax levels pushed by the current Democrats. Even after the tax hikes recently signed by Obama, federal tax receipts are only 17.3% of GDP. That compares to an average of 19.9% from the start of the data series (1940) through 2001. And Americans pay lower taxes, overall, than people in all the other OECD nations except Chile and Mexico.
Or look at healthcare. The healthcare reform pushed through by Obama was essentially Romneycare, and was far more conservative than the reforms pushed by earlier generations of Democrats. Certainly compared to the highly socialized structure of Medicare, it's very conservative. It's arguably more conservative even than the plan Nixon pushed (which was rejected by Ted Kennedy, at the time, who thought we could get something more liberal):
http://www.bostonglobe.com/opinion/2012/06/22/stockman/bvg57mguQxOVpZMmB1Mg2N/story.html
And, of course, if you took all the wealthy nations and sorted our healthcare systems from most liberal to most conservative, the current US system would still be the most conservative.
One one issue after another, with the only major exception being gay rights, the current crop of Democrats looks almost like Republicans next to prior generations of Democrats, and they look center-right or even far-right compared to the mainstream left parties in other wealthy nations.
You are free to argue that Democrats, despite their move to the right, and despite sitting so far to the right relative to other leading nations, are still too far left for your tastes. By trying to frame this as Democrats going off the left end of the Earth just shows a detachment from reality. It's simply untrue. The Democrats of today are a relatively conservative party, both compared to their counterparts abroad and their counterparts in America's recent past.