Question: who did Hillary Rodham Clinton run against in her last senate election ?

Context paragraphs:
United States Senate election in New York, 2006: The 2006 United States Senate election in New York was held November 7, 2006.  Incumbent Democratic U.S. Senator Hillary Rodham Clinton won, by a more than two-to-one margin, a second term representing New York in the United States Senate.  Clinton was challenged by Republican John Spencer, a former Mayor of Yonkers, New York.  Spencer won his party nomination by defeating former national security staffer K. T. McFarland in a primary.

The Seduction of Hillary Rodham: The Seduction of Hillary Rodham is a 1996 book about the early years of Hillary Rodham Clinton written by David Brock.

Hillary Clinton presidential campaign, 2008: The 2008 presidential campaign of Hillary Rodham Clinton, then junior United States Senator from New York, was announced on her website on January 20, 2007.  Hillary Clinton was previously the First Lady of the United States and First Lady of Arkansas prior to her election as U.S. Senator from New York.  She is also the wife of former President Bill Clinton.  Clinton was the source of much media speculation since having expressed interest in being a candidate in the 2008 presidential election since at least October 2002.

Hillary Doctrine: The "Hillary Doctrine" is a term used to describe the agenda of former United States Secretary of State Hillary Rodham Clinton.  In particular, the Hillary Doctrine refers to talks given by Clinton arguing that women's rights and violence against women should be considered issues of national security.  The doctrine encompasses stances she has held before, during, and after her tenure as secretary.

United States Senate election in New York, 2000: The United States Senate election in New York in 2000 was held on November 7, 2000.  Hillary Rodham Clinton, then First Lady of the United States and the first First Lady to run for political office, defeated Congressman Rick Lazio.  The general election coincided with the U.S. presidential election.

Tony Rodham: Anthony Dean "Tony" Rodham (born 1954) is an American consultant and businessman who is the youngest brother of former First Lady of Arkansas, First Lady, Senator from New York and Secretary of State, Hillary Rodham Clinton, and the brother-in-law of former U.S. President Bill Clinton.  His business dealings have sometimes appeared to take advantage of his connections to the Clintons and accordingly have sometimes attracted public scrutiny.

A Woman in Charge: A Woman in Charge: The Life of Hillary Rodham Clinton is a biography of United States Senator, and former First Lady of the United States, Hillary Rodham Clinton that was written by Carl Bernstein and published on June 5, 2007, by Alfred A. Knopf.

Hugh Rodham (born 1950): Hugh Edwin Rodham (born 1950) is an American lawyer and former Democratic Party politician who is the brother of former New York Senator, First Lady, and Secretary of State, Hillary Rodham Clinton, and the brother-in-law of former U.S. President Bill Clinton.

Her Way: Her Way: The Hopes and Ambitions of Hillary Rodham Clinton is an investigative biography about United States Senator, and former First Lady of the United States, Hillary Rodham Clinton that was written by Jeff Gerth and Don Van Natta, Jr. and published on June 8, 2007, by Little, Brown and Company.

United States Senate career of Hillary Clinton: Hillary Rodham Clinton served as a United States Senator from New York from January 3, 2001 to January 21, 2009.  She won the United States Senate election in New York, 2000 and the United States Senate election in New York, 2006.  Clinton resigned from the Senate on January 21, 2009 to become United States Secretary of State for the Obama Administration.

Supporting paragraphs: United States Senate career of Hillary Clinton United States Senate election in New York, 2006
Answer: John Spencer