If Democrats lose control of the U.S. Senate, it won’t be because they didn’t fully unleash the powers available to them in a post-Citizens United v. Federal Election Commission era of politicking.

Related: Senate Majority PAC TV ads per month

Senate Majority PAC, the Democratic super PAC dedicated to holding the Senate, has blasted out about 45,000 Senate-focused television ads this election cycle — more than any other outside spending group.

Related: Tone of TV ads aired by Senate Majority PAC

For context: Senate Majority PAC alone is responsible for roughly one out of every 20 Senate race ads, including those sponsored by candidates and political party committees. In the hotly contested North Carolina Senate race, the super PAC has run more ads than the Republican candidate Thom Tillis, who’s locked in a statistical dead heat with incumbent Democratic Sen. Kay Hagan.

Related: State-by-state TV ad counts for Senate Majority PAC

Senate Majority PAC’s dominance this cycle shows Democrats have largely moved past their initial qualms regarding the outside spending frenzy enabled by Citizens United, which empowered corporations, unions and other special interests to raise and spend unlimited amounts of money to directly advocate for and against political candidates.

Related: Who's buying the Senate?

They are now playing the super PAC game to win. The group’s core contributors are a cross-section of Democratic stalwarts, dominated by billionaires and labor unions with reasons for making sure Democrats continue to control the Senate.

Related: GOP rides cavalry to U.S. Senate majority

Led by seasoned political disciples of Senate Majority Leader Harry Reid, D-Nev., Senate Majority PAC has raised more than $53 million this cycle. As of Friday, it had made $47 million worth of independent expenditures — most in the form of TV ads skewering Republican candidates.

Nearly two-thirds of the money — about $34 million — came from contributors giving half a million dollars or more, according to a Center for Public Integrity analysis of contribution records filed with the Federal Election Commission. That’s roughly the same percentage as marquee Republican super PAC American Crossroads, though that group has reported raising just more than $28 million so far this cycle, far less than Senate Majority PAC.

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Senate Majority PAC’s spending is a fraction of the close to $700 million the Center for Responsive Politics predicts outside groups will spend on the midterm elections. Overall, CRP expects combined spending by Republican candidates, party committees, and conservative-leaning outside groups to outstrip spending on the Democratic side this cycle.

Senate Majority PAC declined to comment for this story, but those facts may explain why Senate Majority PAC contributors are still talking as if they’re big-money underdogs.

There’s more to this story. Click here to read the rest at the Center for Public Integrity.

This story is part of Buying the Senate 2014. Whether Republicans control both chambers of Congress squarely depends on Senate races in a handful of states. Click here to read more stories in this investigation.

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Copyright 2014 The Center for Public Integrity. This story was published by The Center for Public Integrity, a nonprofit, nonpartisan investigative news organization in Washington, D.C.