In 2001 his change of political affiliation tipped the balance of power in the Senate
The answer reveals the balance of power in the two branches of government ... 
political party does not control the White House, the Senate, and the House of .... [
1] There were 50 Ds and 50 Rs until May 24, 2001, when Sen. [DOC] [TLE] McCain Profile: The 'maverick' and President Bush - AZCentral [PAR] Mar 1, 2007 ...