20 years ago, at the end of Ronald Reagan's presidency, Uwe Thaysen ascertained a significant increase in Congressional power opposite the presidency based on his assessment of three determining factors: policies, persons, and parties. His prediction of a long-enduring Congressional self-assertion vis-à-vis the presidency proved well-founded concerning the presidencies of George H. W. Bush and Bill Clinton. Yet the "Republican Revolution" in 1995, the ascension of George W. Bush to the presidency, and the terror attacks of 9/11 changed the combination of the three factors and brought about a new balance of power: The New Republican Congress is the result of electoral change that led to a nationalization of the American party system and to the "Southernization" of the Republican Party. With the parties increasingly homogenous, partisan polarization in Congress reached new heights. Republicans further increased the centralization in Congress with their organizational reforms in the 104th Congress (1995–97), but at the same time weakened it as an institution. Following the terrorist attacks of 9/11, Congress equipped President Bush with far-reaching emergency powers. Altogether, policies, persons, and parties have led to a weakening of Congress vis-à-vis the presidency in the past decade.