When it comes to Democrats and outside money, they've learned their lesson for 2014 — if you can't beat them, join them.
After the shellacking of the 2010 midterms, Democrats vow this year will be different as they embrace super-PACs to raise millions of dollars that will be critical as the look to defend their fragile Senate majority.
But Democrats haven't stopped there — the second prong of their strategy is to encourage the Internal Revenue Service to increase regulation of advocacy groups falling under section 501(c)4 of the tax code, which Republicans rely on disproportionately. These groups include Americans for Prosperity, funded by the Koch brothers, and Crossroads GPS.
Suddenly finding themselves in post-Citizens United world with new fundraising guidelines, Democrats learned a hard lesson four years ago when they let GOP-allied groups outspend them badly. The results was a disastrous election that cost them control of the House and six seats in the Senate.
"In 2010, after Citizens United, Democrats mostly ceded the field as far as the use of outside money and super PACs to advance an agenda and Republicans, Karl Rove and the Koch brothers took full advantage of the Supreme Court ruling," said Rodell Mollineau, a Democratic strategist and former president of American Bridge 21st Century, an opposition research and candidate tracking super-PAC.
President Obama's political team dissuaded donors from outside political groups during his 2008 campaign, effectively dismantling infrastructure of outside groups. They paid dearly for that ambivalence in the 2010 GOP wave year.
"Democrats saw what happened in so many House races across the country in 2010 when Democratic candidates were running competitive campaigns right up until the end and then were overwhelmed with last-minute outside Republican spending," said Andy Stone, a spokesman for the Democratic-aligned House Majority PAC.
"Democratic groups deliberately set up the outside structure that we have to ensure that all of the outside money in Democratic races is being spent as efficiently and effectively as possible," he added.
Now, they're the ones finding themselves on top. Senate Majority PAC, the main super-PAC dedicated to defending the Democratic Senate has raised and spent more than any other super-PAC this cycle, according to CRP.
Independence USA PAC, a super-PAC affiliated with liberal-leaning former New York City Mayor Michael Bloomberg to push increased gun control regulations, ranks second on CRP's list.
House Majority PAC, which was created to help Democrats recapture the House, ranks third, having raised $7.8 million and spent $1.75 million this cycle, according to CRP. The group will reportedly spend $50 million on House races this year, though Stone would only confirm that it will spend at least as much as it did in 2012, $36 million.
CRP lists the Service Employees International Union, which has raised $2.2 million and spent $1.6 million at No. 4 on its list of biggest super-PACs in 2014.
Two conservative groups, Americans for Progressive Action and Club for Growth, ranked fifth and sixth on the list.
American Crossroads, a super-PAC co-founded by Mike Duncan and Steven Law, raised $26.6 million and spent $21.7 million on independent expenditures in 2010, more than any other super PAC that year, according to CRP. Crossroads GPS, the affiliated 501(c)4, collected $43 million in the 2010 cycle.
This election cycle both groups have raised far less after producing disappointing results in the 2012 election. American Crossroads and Crossroads GPS raised $6 million in 2013.
American Crossroads recently launched ads against Sen. John Walsh (D-Mont.), who was appointed to replace former Sen. Max Baucus (D-Mont.) and is running for a full term in November, and Alex Sink, the Democratic candidate in Florida's 13th House district.
So far this election cycle, CRP calculates that liberal non-party committees have outspent their conservative counterparts, but that total does not include the estimated $27 million already spent by Americans for Prosperity.
In 2010, groups qualifying under 501(c) of the tax code outspent super-PACs by a 3-to-2 ratio.
"So far it is more narrow," CRP's Maguire said of the gap between spending by social welfare groups and super PACs.
Democrats and their allies have also raised millions of dollars through 501(c)4 groups such as Patriot Majority USA and the League of Conservation Voters.
But at a time when Democrats are more reliant on super-PACs, Democratic senators are pushing the IRS to promulgate stricter rules for 501(c)4 groups. The IRS now says social-welfare activity must be the primary activity of 501(c)4s, but gives them wide latitude by not classifying voter registration drives and electioneering ads as political activity. Electioneering communications can mention a federal candidate but stop short of advocating for his or her election or defeat.
Correction: An earlier version of this story misidentified Gillespie's role with Crossroads GPS.