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Nicholls was unable to gain sufficient support to oust Flegg in a closely divided caucus , but following ongoing tension , Flegg resigned as leader on 4 December 2007 and was succeeded by compromise candidate Mark McArdle .
 Nicholls, Flegg, Flegg, Mark McArdle
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Nicholls, Flegg, Flegg, Mark McArdle