question: Which Democratic US Senator set a record for margin of victory with 71.2% in the 2004 election only to be surpassed by Kirsten Gillibrand's 72% of the vote  in 2012?
answer: Chuck Schumer
context: Title: Ambrose Hundley Sevier
  Passage: Ambrose Hundley Sevier (November 4, 1801 – December 31, 1848) was an attorney, politician and planter from Arkansas.  A member of the political Family that dominated the state and national delegations in the antebellum years, he was elected by the legislature as a Democratic US Senator.
  Title: Kirsten Gillibrand
  Passage: Kirsten Elizabeth Gillibrand (née Rutnik; ; born December 9, 1966) is an American attorney and politician who since 2009, has served as the junior United States Senator from New York, alongside the Democratic Leader of the United States Senate, Chuck Schumer.  Before the Senate, she served for two years (2007-09) in the United States House of Representatives, representing New York's 20th congressional district.  She is a member of the Democratic Party.
  Title: United States Senate election in New York, 2004
  Passage: 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.
citations: United States Senate election in New York, 2004 Kirsten Gillibrand