Lark: Well then the sources speak for themselves as NJ has said Marx said that in Holland and the US Socialism would come non-violently through the ballot box...I think you'll want to differentiate between Marx and the Marxists.
Barry: Actually, it was ENGELS who (controversially) said the above---see his introduction to Marx's Class Struggles in France.
Chuck: Marx said it too - in a speech he gave in Amsterdam on September 8, 1872 after a congress of the first international:
"...we do not deny that there are countries - such as America, England, and if I were more familiar with your institutions, I would perhaps also add Holland - where the workers can attain their goal by peaceful means." (The Marx-Engels Reader, 2nd edition, edited by Robert C. Tucker, p.522, "The Possibility of Non-Violent Revolution")
Adam Buick of the SPGB also points out that:
"In 1880 we find him (Marx) drafting a declaration of principles for a workers' party in France itself in which workers were urged to turn 'universal suffrage from the instrument of fraud it has been up to now into an instrument of emancipation.'" (DB # 91, p.10, Sep-Oct 1998)