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Grassley a conservative Republican and his Senate colleague from  Iowa  liberal Democrat  Tom Harkin  have achieved enduring success in this state largely by mastering the politics of farm issues .
 state or provinces of residence: Iowa, Tom Harkin
Given options, please tell me the relationships of all the listed entity pairs.Output format is "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} 
 Entity Pairs:  Iowa, Tom Harkin 
Answer:
 state or provinces of residence: Iowa, Tom Harkin