Principles versus electability
More and more people are starting to see why the Republican Party's fall from grace was painfully obvious and inevitable:
A vacancy occurs in Congress. Who's going to fill it? The GOP establishment has its favorite son, an amiable fellow who thinks he'd be one heck of a congressman. And then there are other candidates, probably three or four, who lay hold to the label of true conservatism. They fight it out. Leaders of many right-of-center groups endorse the good old boy. The good old boy is hailed for his electability. He may have his flaws, but he can win, we're assured. So voters nominate and then elect Congressman Good Old Boy.
Congressman Good Old Boy doesn't give a lick about issues like right to life or limited government. Sure, he may personally believe in some of these things, but they have nothing to do with why he got into politics. The congressman's focus is on getting re-elected, so he works his darnedest to bring home tens of millions of dollars in earmarks and to impress a cross-section of special interest groups.
Congressman Good Old Boy is focused on appropriating money, doling out favors, defending the party establishment, and getting re-elected. Rinse, lather, and repeat a hundred times, and you have the story of two-thirds of the Republicans in Congress.
The problem the Republican Party faces is twofold. First is the division between the GOP's leadership and its membership. Scott Rasmussen has defined a divide in polling between the mainstream (or "populist") mood and [2] the political class. This is the basic divide within the GOP.
One of the dirty non-secrets of the GOP's electoral demise is that most voters care more about seeing the system run efficiently and reliably than they do about most political issues. Had the Republicans kept us out of Iraq, run a budget surplus that was being used to pay down the national debt reliably year-after-year, kept taxes low and avoided the earmarks and other financial scandals, they'd still be in power today. They'd have had the political capital to appoint a strongly libertarian-conservative Supreme Court and actually bring about an end to Roe v. Wade among other things that matter to their much more conservative base. The moderate and liberal voters would have been far more tolerant of things like Roe v. Wade being reversed by a SCOTUS appointed by a government that ran a tight ship of state that really made the government work for the public on most issues close to home.
The "moderates" like Specter were also often the ones who were the least committed to the conservative base's principles and to running an efficient operation. The conservative Republicans who have made fighting graft, inefficient spending, government growth, etc. are not the ones losing their support today. Rather it is the unprincipled moderates who go whichever way the wind blows, and are focused more on their own office than principles which are facing the toughest time.

In the recent discussion abvout principle vs winning, the side supporting "winning" fail to understand that the principled side is recognizing that they are winning nothing when they support an unprincipled candidate. An (R) on the map is not enough. If the point of elections is to get your ideas and principles represented in the legislature, voting for someone who will not accomodate your positions is political suicide with a tiny figleaf of "at least we are involved in the process".
I will never again vote for someone whose only merit is, "he isn't as bad as the other guy".