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?
United States Senate election in New York, 2004:  The record was surpassed by Kirsten Gillibrand when she won re-election to a first full term in 2012 with 72% of the vote.
i don't know