In 1938, Stynes signed on behalf of the American GAA an Irish-American petition for the release of Frank Ryan, the IRA leader imprisoned by Franco's Nationalists during the Spanish Civil War for fighting in the International Brigades. In 1939, he was indicted and charged with attempting to bribe US Customs officials while operating as an agent for the Irish Sweepstakes. He was politically active in Clan na Gael, and after 1948 was leader of the few branches that had remained loyal to the rump of the IRA. In 1949, Stynes supported a decision, which split the Clan, to use its funds for a monument in Dublin to Seán Russell rather than retaining them for a future IRA campaign. After the decline of Clan na Gael, and the outbreak of the Northern Troubles, he was sympathetic to NORAID. He sided with Republican Sinn Féin after its 1986 split from Provisional Sinn Féin, and in 1987 he co-founded the National Irish Freedom Committee (NIFC; ) for its American supporters. Most younger and American-born Irish republicans remained with NORAID and Provisional Sinn Féin.