FYI..I happen to agree with your basic premise..the idea of sitting out, or voting for a third party, in a Hillary v Rudy 2008 race for the WH, to be smacks of a loss of sanity, though a principled loss, to be sure..and there are many ehre who have that viewpoint..Some you may be able to convince to reconsider, others are zealous purists..and we do need those..they are the conscious of the conservative movement...but we must keep them within the Republican tent..as one who cut his political eyeteeth in 1964 handing out..or trying to.. Goldwater literature in the Bronx..not an easy thing to do..we didn't go off and hide...we took back the party..
My phrasing and tact can always be improved but, frankly, I have little patience with the 3d party crowd and do like antagonizing them. In fact, that is one of the reasons I adopted my screename.
I have no problem with 3d parties endorsing Republican or conservative candidates when the opponents are clearly clueless Leftists such as Senator Buckley's party in NY decades ago, the Conservative Party. That way they can pursue their principles without damaging conservativism. But most are not intelligent enough for that tack.