Bringing to light the resemblance of the American party's politics to those of Lassalle, Daniel De Leon emerged as an early leader of the Socialist Labor Party. He also adamantly supported unions, but criticized the collective bargaining movement within the United States at the time, favoring a slightly different approach. The resulting disagreement between De Leon's supporters and detractors within the party led to an early schism. De Leon's opponents, led by Morris Hillquit, left the Socialist Labor Party in 1901 as they fused with Eugene V. Debs's Social Democratic Party and formed the Socialist Party of America.