13015
Incumbent Democratic United States Senator  Tom Harkin  sought re-election to a third term in the United States Senate and he was challenged by United States Congressman Jim Ross Lightfoot from  Iowa  's 3rd congressional district .
 state or provinces of residence: Tom Harkin, Iowa
Given a phrase that describes the relationship between two words, extract the words and the lexical relationship between them. The output format should be "relation1: word1, word2; relation2: word3, word4". 
Option: cities of residence, top members employees, members, alternate names, origin, state or provinces of residence, title of person, spouse, city of headquarters, NA, founded by, state or province of headquarters, employee of, countries of residence, country of birth, founded, subsidiaries, country of headquarters 
Text: {0} 
Answer:
 state or provinces of residence: Tom Harkin, Iowa