The role of money in elections was certainly one of the big stories of 2012. But it's been hard to know exactly what the impact of ramped-up spending was. The independent news Web site, Pro Publica, has been investigating the issue. Reporters there have come up with some surprising information. The site's latest story concludes that so-called "dark money" helped Democrats hold a key Senate seat. "With control of the Senate at stake," says Pro Publica, "liberals hit the streets and bought ads for a libertarian candidate who likely siphoned crucial votes away from the Republican challenger."

The story is part of a series Pro Publica has dubbed Campaign 2012: Revealing Dark Money and Big Data. Reporters are “following the money and exploring campaign issues in the 2012 election you won't read about elsewhere,” the site says.

Given the baffling state of campaign finance in the post-Citizens United world, the series is worth a look. The questions asked are provocative. The evidence gathered challenges widely held assumptions.

Topics of past stories include:

  • How Nonprofits Spend Millions on Elections and Call it Public Welfare
  • Who’s Making Money From Campaign Spending?
  • PAC Track
  • Who Are the Super PACs' Biggest Donors?
  • Reverse Engineering an Obama Email Campaign

Read the latest story in the series, In Montana, Dark Money Helped Democrats Hold a Key Senate Seat.