Waterbury – First-term U.S. Rep. Elizabeth Esty won re-election in the state’s most competitive congressional district Tuesday, fending off a challenge from Republican Mark Greenberg in an election year considered to be tough for Democrats. The 5th District, which includes Danbury, Waterbury and New Britain as well as rural Litchfield County and parts of the Farmington Valley, was considered the GOP’s best shot at gaining a Congressional seat in Connecticut.