In New York City they have Conservative and Liberal Parties (among others) that DO wield some sway in the candidate selection process -- in Israel they have a multi-patry system which produces a lively combination of personality and idea-based politics, where the ideas of each party are more adhered to reliably.
In a multi-party system you still have the eternal battle of insider-versus-outsider yet each party holds its ideals and throws in ad-hoc to the outsiders or the insiders, rather than becoming a big-tent ideals-mean-nothing party.
I have no idea what this means. Could you try communicating in English?