The result, Podhorzer said, was like "taking off the handcuffs." The AFL-CIO and other unions conducted door-knocking, phone-banking and advertising campaigns this year aimed at the general public in elections they hoped to influence, and made a big difference.

It was a similar story for Credo, a for-profit phone company that supports progressive causes. As a corporation, it was subject to pre-Citizens United campaign-finance restrictions that prevented it from spending money on campaigns. But this election cycle, the company formed a super PAC and targeted 10 vulnerable Republican congressional incumbents with an intensive, volunteer-based campaign of field organizing in their districts. Five of them, including firebrand Florida Rep. Allen West, were defeated.

"Allen West raised $17 million, spent $13 million and lost by a couple thousand votes," Becky Bond, political director of Credo Mobile and president of the Credo Super PAC, boasted. "With just a few hundred thousand [dollars], we made the difference."

At first, Bond said, the group worried that its members would recoil from the embrace of Citizens United that the super PAC represented. But they found exactly the opposite. "We got very little blowback at all," she said. "People were very excited that this was our super PAC. People thought the super PAC was super."

Both Workers' Voice and the Credo super PAC focused on ground organizing and eschewed paid advertising. They saw their ability to use data-based, person-to-person campaigning as an asymmetrical advantage against better-funded groups on the right. But another super PAC on the left, Priorities USA, focused on using television ads to discredit Mitt Romney; despite being massively outspent by GOP groups, including the $300 million-plus raised by Karl Rove's Crossroads groups, Priorities has been widely cited for its superior effectiveness. Its ads helped cement the image of Romney as a corporate raider that would prove such a liability in the general election.

This may be one of the major takeaways of the 2012 campaign: When liberals learned to stop worrying and love Citizens United, they benefited from it more than the conservatives who supported the decision.

Nonetheless, they insist they'd still prefer the situation--and the decision--be reversed. "We're against Citizens United. We're trying to overturn it. We would close down every super PAC if we could," Bond said.

But with the current state of affairs in campaign finance looking unlikely to change in the near future, progressives are seeing the silver lining. "Labor obviously has a lot of money," Podhorzer said. "We could have given it to Priorities and the House Majority Fund, and what we would have had on November 7 would be canceled checks."

Instead, in its volunteer-powered super PAC, the union has a standing army. Since Election Day, the members of Workers' Voice have kept up the pressure on potential swing-voting members of Congress, urging them not to compromise on taxes and entitlements in the fiscal-cliff talks.

"What we have now is hundreds of thousands of volunteers and a recognition by a lot of politicians that they need to listen to the people they represent," Podhorzer said. "That's a far better outcome .... That doesn't happen when we write checks, no matter how big."

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