Jon Chait makes just that claim, in a long essay that says real liberals shouldn't be that hard on Obama.
Ahh, there's the problem. With both America and Jon Chait's thought processes.
Fact is, of course, that America's the most conservative of the advanced democracies, especially if we exclude Japan and South Korea. As a result, American liberals include less liberal types, who argue about what's practical, what's achievable, and what's really that liberal.
Canada? Past huge history of *conservative* disorganization.
Britain? Old vs. new Labour is still an issue, especially with Lib Dems selling out to the Conservatives. Still more organized than the U.S.
France? True, recently, its Socialists are struggling, but they have had a strong past.
Germany? The only issue is that of Social Democrats refusing to coalition with the former Communists of the "new left." The new left will eventually weaken enough to eliminate that worry.
Elsewhere in Western Europe, socialist and social democratic parties, either single ones such as Spain's Socialists, or coalitions such as in Scandanavia, have had no disorganization issues.
So, the real fault is with America in general and Chait's analysis in particular far more than with American liberalism.