THE STRUCTURE OF CONGRESS| 275sibility is to get their party’s legislative agenda through Congress; their positive
powers in this regard are agenda control and persuasion. Leaders’ success largely
depends on their personal skills, communicative abilities, and trustworthiness.
Some of the most successful leaders, such as Lyndon Johnson (D-Tex.), majority
leader of the Senate from 1955 to 1961, and Sam Rayburn (D-Tex.), Speaker of the
House for more than 17 years, kept in touch with key members on a daily basis.10
020304050607080%Percentage of roll call votesHouse
Senate196219641966196819701972197419761978198019821984198619881990199219941996199820002002200420062008 2011PARTY VOTES IN CONGRESS, 1962–2011
These graphs make two important points. First, partisanship has increased in the last two decades, both in terms of the
proportion of party votes and the level of party unity. Second, despite these increased levels of partisanship, only about half
of all votes in the House and Senate divide the two parties. Given these potentially confl icting observations, how would you
assess the argument that partisanship in Congress is far too intense?FIGURE » 9.5A
030405060708090100%Party unity score196219641966196819701972197419761978198019821984198619881990199219941996199820002002200420062008 2011House Republicans
House Democrats
Senate Republicans
Senate DemocratsPARTY UNITY IN CONGRESS, 1962–2011
FIGURE » 9.5B
Sources for 10.6A and 10.6B: Data from Norman J. Ornstein, Thomas E. Mann, and Michael J. Malbin, Vital Statistics on Congress: 1999–2000 (Washing-
ton, DC: CQ Press, 2000), pp. 201–3, and more recent editions of Congressional Quarterly Almanac.