Democratic Senate president Bill Ferguson in July said transparency was 'essential'
Liberal partisans hold at least 40 percent of 'independent' slots on body that will redraw Michigan's political map
Holder said he supports 'nonpartisan commissions to draw electoral lines so neither party benefits'
The group spent nearly $40 million in the 2018 midterm cycle for pro-choice candidates
Former president now 'tired of politicians manipulating maps' for political gain
Ruling says federal courts must stay out of state gerrymandering challenges
'We'll be honest—we're disappointed'
Holder-led PAC may owe Democrat gains more to billionaire activists