Since the great historical half-reversal of Liberals with the FDR admin and the New Deal, Liberal ideology has had a fundamental contradiction , for and against _free_ markets.
The original Liberals , both in the US and Europe, were distinguished ideologically by their advocacy of laissez-faire, free markets. That is, they were ideologically-theoretically for the government-state leaving them alone to their freedom of trade and enterprise (Actually, even then there was state-monopoly monarchism, with the crowns granting monopolies and backing up the bourgeoisie with military) The states then were monarchies, a transitional form out of feudalism.
FDR's policies constituted a "half-revolution" of liberalism in that it reverses the fundamental liberal ideological tenet of keeping the state out of the free market; and even more taking on some of the reform demands of socialists on behalf of the working class. It put the big contradiction into American liberalism, which in Europe got into the social democratic parties: pro-free "markets"-capital and pro-workers which is realistically anti-free "markets"-capital. "Free market" means "leave the capitalists alone to exploit the working class in every which way and as much as they can think of."
Neo-liberalism, in this regard, is a sort of negation of the negation of FDRism. It is a return ( on a higher level) to the original free market ideology of paleo-Liberalism.
Since FDR, the US Democratic Party has this high contradictoriness. So, for it ideology is very difficult to have. For, ideology is a logically consistent , i.e. non-contradictory, political theory.
Charles