Here's my response to a blogger who was pushing for the "Big Tent" for the Republican Party. It was the typical argument -- we can't win without the support of whole bunches of people who don't normally vote for the GOP, we can make more progress by building coalitions than by dividing into little groups, etc. It made alot of sense, of course, but also missed a critical dynamic in party and election politics.
I was discussing abortion politics, but the same argument could be made in favor of fiscally conservative politics, etc. But fiscally conservative politics cannot make up for offending and getting rid of moral conservatives. Bob Schaffer tried that in 2008 (stupidly, since he lost many Christian supporters while liberals remembered he had always been pro-life - he lost votes from his base without picking up any on the other side, which is the same problem the GOP in general faces), and Schaffer fell on his face.
I used to believe in a "big tent," but I've since learned its folly. Without principles, we get nowhere. Reagan didn't offer us a big tent -- he offered us principles, which were broadly appealing and which inspired those who might not otherwise agree with him to vote for him.
There was once a "big tent" party -- the Whigs -- which tried to appeal to northerners and southerners alike by not taking strong stands on controversial issues like slavery. Do you know what happened to them? Probably not, because unless you study the history of the period no one even remembers who they were. In actuality, they split into two parties.
Did both parties lose? Did both of these "third parties" devastate themselves by shedding the big tent, leaving their major party behind, and dividing over matters of misguided principles?
No. One of those parties -- the Republican Party -- came to dominate the politics of the next several decades. For 70 years, in fact, and for a great portion of the century afterward, too.
They stood on a major principle -- opposition to slavery -- which held such a broad appeal that they succeeded where the wishy-washy "big tent" party failed.
The Republican Party today has the opportunity to stand on another major, unifying principle which could inspire them to victory. They could pledge to ban abortion and recognize the Personhood of the unborn child so he or she is not considered property like the slaves.
The Republican Party will succeed or die on this principle. Any attempts to remove the pro-life principle from the platform (which is what "big tent" means, in almost all cases), will destroy the party so that a half-century from today the Republican Party will be as well known as the Whigs are today.
Those "divisive" Christian Conservatives are the base of the Republican Party (and, from what I've found, the base of the Tea Party conservatives too) -- they've handed victory to the GOP in 5 of the last 8 presidential elections, but they're feeling ignored and betrayed. The Republicans can take them or leave them. If they leave them, they will energize another party and make them victorious instead.