Yeah, and and there was this guy named Abe Lincoln, who got crushed in his first electoral adventure as a Republican after leaving the Whig Party. I wonder how he turned out?
The other fact is that is NOT the Democrats who are riving the GOP. Why would they? Especially when the Establishment Republicans are doing such a good of it on their own.
And don't blame anyone else other than the GOP Establishment. Remember that the Tea Party stuck with the GOP, despite attempts by the Establishment to co-opt the Tea Party and then purge them when that failed. The Libertarians dissolved their own party to join the Republicans after they were convinced (deceived?) into believing they had a better shot at re-shaping policy within the GOP.