It's not a two party system, that's the lie that makes it unconductive to change.
While our political system was not legally instituted as a two-party system, it devolved into a two-party system almost immediately. Though the occasional party switches were just that—a switch to reform one of the major parties. Third parties have always been the result of a charismatic front man whose “party” lasted less time than the founder.
The Republican Party is overdue for another such switch, but I do not think the greater portion of its constituency has the conviction or the will to do so. Americans have become slaves to the moment, and Republicans are no less so. Ignorant of history and obstinately blind to the future, they race headlong to their own destruction. Expediency has a place in some battles, but it is no substitute for strategy.