Question: In what year did the winner of the 2004 United States Senate election in Kansas run for president but withdrew before the primaries?

Context paragraphs:
United States Senate election in Indiana, 2010: The 2010 United States Senate election in Indiana took place on November 2, 2010, alongside 33 other elections to the United States Senate in other states and elections to the United States House of Representatives and various state and local elections to fill Indiana's class III United States Senate seat.  Incumbent Democratic U.S. Senator Evan Bayh decided in February 2010 to retire instead of seeking a third term shortly after former U.S. Senator Dan Coats announced his candidacy for Bayh's contested seat.  No Democratic candidate submitted enough signatures by the deadline to run, leading Democratic officials to choose U.S. Congressman Brad Ellsworth to be the nominee.  The Libertarian Party nominated YMCA instructor Rebecca Sink-Burris, who had previously run against Evan Bayh in the United States Senate election in Indiana, 1998 but with less success than in this election.  Republican nominee and former U.S. Senator Dan Coats won the open seat.

Sam Brownback: Samuel Dale Brownback (born September 12, 1956) is an American politician and diplomat who is the 46th Governor of Kansas.  A member of the Republican Party, Brownback was first elected to the U.S. House of Representatives during the Republican Revolution of 1994, representing Kansas's 2nd congressional district for a single term, before running in a 1996 special election for the U.S. Senate seat previously held by Bob Dole.  He won the special election and the following two regular elections, serving until 2011.  He ran for president in 2008, but withdrew before the primaries began and endorsed eventual Republican nominee John McCain.  He was elected Governor of Kansas in 2010 and took office in January 2011.

United States Senate election in Kansas, 2004: The 2004 United States Senate election in Kansas was held November 2, 2004.  Incumbent Republican U.S. Senator Sam Brownback won re-election to a second term.

United States Senate election in Alaska, 2004: The 2004 United States Senate election in Alaska took place on November 2, 2004 alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives, various state and local elections, and the presidential election of that year.  Incumbent Republican U.S. Senator Lisa Murkowski of Anchorage, sought election to her first full term after being appointed to serve out the rest of her father's unexpired term when he resigned in December 2002 to become Governor of Alaska.  Her main challenger was Democratic former Governor Tony Knowles, her father's predecessor as governor.  Murkowski won by a slight margin.

United States Senate election in Iowa, 2004: The 2004 United States Senate election in Iowa was held on November 2, 2004.  Incumbent Republican United States Senator Chuck Grassley ran for re-election to a fifth term in the United States Senate.  Grassley and former State Senator Arthur A. Small won the Republican and Democratic primaries, respectively, unopposed, and faced each other in the general election.  Though this election coincided with the highly competitive presidential election, Grassley was in little danger of losing his seat and defeated Small handily.

United States Senate election in Kansas, 2016: The 2016 United States Senate election in Kansas was held on November 8, 2016, to elect a member of the United States Senate to represent the State of Kansas, concurrently with the 2016 U.S. presidential election, as well as other elections to the United States Senate in other states and elections to the United States House of Representatives and various state and local elections.  The primaries were held on August 2.

United States Senate election in California, 2004: The 2004 United States Senate election in California took place on November 2, 2004 alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives and various state and local elections.  Incumbent Democratic U.S. Senator Barbara Boxer ran for re-election and defeated Republican former Secretary of State Bill Jones.  Boxer's 6.96 million votes set the all-time record for the most votes cast for one candidate in one state in one election, although it was surpassed by Senator Dianne Feinstein's 7.75 million votes in 2012.

United States Senate election in Arkansas, 2004: The 2004 United States Senate election in Arkansas took place on November 2, 2004 alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives and various state and local elections.  Democratic incumbent U.S. Senator Blanche Lincoln ran for re-election.  Lincoln won re-election, while President George W. Bush carried the state with almost the same margin of victory.

United States Senate election in New York, 2004: The 2004 United States Senate election in New York took place on November 2, 2004 along with elections to the United States Senate in other states as well as the presidential election, elections to the United States House of Representatives and various state and local elections.  Incumbent Democratic U.S. Senator Chuck Schumer won re-election to a second term with 71.2% of the vote, a then-record margin of victory for any statewide candidate in New York's history.  The record was surpassed by Kirsten Gillibrand when she won re-election to a first full term in 2012 with 72% of the vote.

Alabama elections, 2004: The 2004 United States Senate election in Alabama took place on November 2, 2004 alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives, various state and local elections, and the presidential election of that year.

Supporting paragraphs: United States Senate election in Kansas, 2004 Sam Brownback
Answer: 2008