A newspaper editor, De Leon joined the Socialist Labor Party in the US in 1890 and soon became one of its leaders. He led a radical faction that seceded from the Knights of Labor in 1895 and formed the Socialist Trade and Labor Alliance (STLA). The STLA was later absorbed by the Industrial Workers of the World (IWW), which he helped found in 1905. After being refused a seat at a 1908 IWW convention by extremists who favored violent tactics over political action, he founded what organization? Discuss