A liberal Protestant whose politics were similar to Henry Grattan, he employed all his eloquence to oppose the illiberal policy of the Government, and also the Union with Britain. Curran stood as Member of Parliament (MP) for Kilbeggan in 1783. He subsequently represented Rathcormack between 1790 and 1798 and served then for Banagher from 1800 until the Act of Union in 1801, which bitterly disappointed him; he even contemplated emigrating to the United States. He also visited France in the 1780s and in 1802 at the time of the Treaty of Amiens, and considered that an Ireland ruled by the United Irishmen under French protection would be as bad as, if not worse than, British rule.