He swung left for the election, but staying left would drive off the right end of the party. So he swung right, culminating in 2011. Then they figured out they had gone too far right, and swung left again for 2012.
If you lose a lefty vote but pick up a righty vote you gain one vote because for every righty vote you get it removes that vote from the R candidate. And it turns out that well over half the lefties will vote for you anywayz because (unlike the right) there is nowhere to turn.
In the general election.
That's why primaries are so critical to steering the party. The dynamic you describe doesn't work - you can't pick up "Reagan Democrats" or "Clinton Republicans" because they don't get to vote in the primary for the opposite party.
The crazy Republicans turned their party right by losing a lot of primary elections. Just being present in the primary forced the mainstream Republicans to defend their right flank, and running too far to the middle in the general earned the mainstream candidate a primary opponent in the next election that could beat them.
H. Clinton-Sachs isnt even going to bother to lie to the left. She knows to beat Bush she needs to steal votes from him.
Assuming she's the candidate in the general. I seem to remember lots of people insisting no one could possibly beat her in 2008.
Again, stop ignoring primary elections. They are the most important elections we have.
(And you should also stop ignoring mid-terms and local elections. They're more important than top-of-the-ticket, despite all the media focus on presidential elections)