 The political rivalry between Osmeña and Roxas, and their respective supporters, began in late May 1945 or even before the Congress opened its first session.After Congress convened, it became apparent that the Roxas bloc (later known as the Liberal Wing of the Nacionalista Party) would in due time separate from the ruling Nacionalista Party led by Osmeña.Hence, Osmeña's allies, particularly in the House of Representatives and the Cabinet, exerted every effort to prevent Roxas from using the Congress as his base of political support during the Liberation period.