An inclination to be partisan or biased; partiality(noun)
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Use "partisanship" in a sentence
"At a battery factory in Michigan this past week, he urged Americans to pressure members of Congress to stop what he called partisanship and gridlock that he said have undermined public confidence."
"They absolutely reject what they call partisanship and what I would call respect for readers and their legitimate interests."
""Evan Bayh has been around long enough to know that partisanship is normal part of the process," said Nathan Gonzalez, political editor for the Rothenberg Political Report."