As a member of the GOP, you stand a better chance of booting out an elected Republican whose politics you don't like and impacting the Party to move in your direction, than you would trying to get an elected Democrat to come around to your way of thinking.
You can't accomplish either thing by leaving the Party system.
You can also work and support a third Party, and you will feel good about yourself...but that's all you'll accomplish in the real world, other than perhaps help get Democrats elected.
If you can't understand something that basic, you will never understand Party politics.
Or politics for that matter.
However, real conservative, and registered Republican voter, deliberately voting for a liberal who opposes most or all of the Republican plank, running as a Republican just makes no sense. If someone like that comes out of the primaries, like Specter did, I'd just not vote. Wouldn't vote for them, wouldn't vote for any of the other candidates, since if the Republican candidate in a general election isn't a real conservative, that means that NO real conservative has a chance of winning. Democrats don't put up real conservatives against liberal Republicans. A race like that is pink vs. pinker. While I don't think Toomey would have won in PA (still too democrat leaning), if I was a resident there, I would have voted for Toomey in the primary, and if left with Specter being the Republican choice, I don't know if I'd vote in that Senate race at all. To vote for a Specter type Republican is to knowingly vote for someone who is pro-choice, pro-gay marriage, etc so on, who is agains most of the Republican plank, and votes with the democrats almost as often as with his own Republicans. You really think voting for someone like that, a REAL pink RINO is the obligation of any dedicated strong conservative voter? That just makes no sense to me, and I'm someone who over the years has fussed at people who are really conservative for voting outside the party. To do so, I'd be voting for someone who disagrees with most of my political beliefs and ideals. I'd have to swallow hard and go home and take a shower right away. Because I just became part of the problem. Propping up some RINO RepublicRAT who doesn't stand up for the plank of the party he claims to belong to. How do you do that? This is where my "Christian first" belief comes in. It is not proper to support someone you KNOW does not believe correctly.