According to a new report released Monday by the Sunlight Foundation, 78% of 2012 outside election spending can be attributed to the 2010 Citizens United ruling, which allows unregulated amounts of corporate and otherwise outside campaign donations.

As of Sunday, outside spending hit roughly $465 million, more than double the total for the entire 2010 campaign. This election cycle is the first to follow the Supreme Court's landmark Citizens United decision.

Of the $465m of outside money that has been spent on US congressional and presidential campaigns so far, at least $365m can be directly attributed to funds enabled by Citizens United. Super Pac spending alone amounts to $272m, according to the statistics laid out in the report.

Almost $93 million was donated from corporations, trade associations and non-profits. The latter have been allowed under the Supreme Court ruling "to spend in unlimited amounts and...because of their tax status, are not required to disclose the source of their funds to the Federal Election Commission," states Kathy Kiely at the Sunlight Foundation.

"This money enabled outside groups to run shadow campaigns for or against candidates of their choice."

The Guardian adds:

The 2010 ruling by the supreme court in the case of Citizens United vs Federal Election Commission allowed corporations and unions to spend unlimited money on campaigning, enabling Super Pacs to spend unlimited amounts as long as they had no coordination with the candidates they support.

In reality, those running Super PACs have often have close ties to political parties. Former George W Bush adviser Karl Rove runs the conservative American Crossroads Super Pac, while Restore Our Future, a pro-Mitt Romney Super Pac, was founded by former Romney aides. [...]

The Sunlight Foundation's data shows a heavy skew towards negative campaigning, with $99.2m so far spent supporting a candidate and $360.7m opposing a candidate. Some $131.1m has been spent on communications opposing President Barack Obama, with a relatively small $50.7m spent opposing Mitt Romney.