Illustration by Sam Island for TIME

Last month, Republican congressman Joe Heck got a taste of the kind of attack Democrats have been complaining about for years. Against unsettling background music and grainy photographs, the 30-second TV spot replayed an audio clip, plucked out of context, of Heck saying, “The role of Congress is not to create jobs” and charged him with helping shut down the federal government. The ad finished with the telltale indicator of unlimited third-party donations that have come to define campaign finance in recent years: “House Majority PAC is responsible for the content of this advertising.”

It may as well have added, “If you can’t beat ’em, join ’em.” House Majority PAC is one of several major Democratic super PACs formed to beat Republicans at their own game, and this year, for the first time, it looks as if they’re succeeding. Catching cash-strapped Republicans off guard, Democratic groups have outraised and outspent their GOP counterparts in 2013 by 2 to 1. As Republicans race to catch up, Dems hope to keep the advantage through better coordination and message unity among their super PACs.

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President Obama excoriated the Supreme Court in his 2010 State of the Union address for its decision in the Citizens United case. The ruling overturned key campaign-finance legislation that blocked these loosely regulated behemoths, which can raise unlimited amounts of money to sway elections as long as they say they are not coordinating with a candidate. That fall, Republican super PACs outspent Democratic ones by $12 million, helping the GOP add 63 seats in the House of Representatives and six in the Senate in a historic, crushing midterm victory.

In response, Democrats formed four major super PACs to advocate for their candidates and attack the Republicans: Priorities USA Action, House Majority PAC, Senate Majority PAC and American Bridge 21st Century. At first, it wasn’t easy to raise money, with so many progressives decrying super PACs. Congressional Democrats were pushing campaign-finance reform, and donors in some cases tried to keep their friends from giving to the groups. “We were sort of the hated stepchild of the Democratic Party,” recalls one aide.

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But the pro-Romney super PAC Restore Our Future convinced many Democrats they had to set their principles aside. In January 2012, Obama campaign manager Jim Messina looked at Restore’s numbers and told image-meister David Axelrod, “This is a problem.” Weeks later, Obama quietly sanctioned Priorities USA Action and authorized aides to speak at its events. After raising a paltry $58,815.83 in the month before Obama’s blessing, Priorities took in $2 million in the four weeks after it. By the end of 2012, Chicago media mogul Fred Eychaner had given $4.5 million to Priorities and kicked in $9 million more for House and Senate races.

In 2013 all pretense went out the window. Billionaire donors like New York City Mayor Michael Bloomberg and California environmental activist Tom Steyer spent millions via super PACs targeting Virginia Republican gubernatorial candidate Ken Cuccinelli’s gun-control and climate-change policies. Earlier this year, Steyer donated $1 million to back Ed Markey for John Kerry’s vacant Senate seat. The Democratic Governors Association now moves most of its money through its super PAC, DGA Action.

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Democrats argue that their embrace of super PACs is a means to an end. Steyer’s political strategist Chris Lehane says liberal donors are “engaged not to impact politics so as to help their own personal self-interests but instead to try to help get people elected who will push for policies like climate and gun safety that are in the broader public interest.” Critics like Lindsay Mark Lewis, executive director of the Progressive Policy Institute, say that argument “amounts to ‘My billionaire is a cleaner billionaire than yours.’”

But more practically, Democrats admit they would be foolish to unilaterally disarm in a war they didn’t choose to wage. They say if they ever secure the Supreme Court, the White House, the House of Representatives and a filibuster-proof majority in the Senate, they’ll work to get rid of super PACs and pass the DISCLOSE Act, which would shine a light on other shadowy donations. Even the most avid fundraisers don’t expect liberal super PACs to succeed that well anytime soon.