Right-leaning Super PACs topped their Democratic rivals by a factor of nearly three-to-one from the start of 2011 through June 30, according to a Sunlight analysis of filings made through midnight Friday. In the first eighteen months of the presidential election cycle, Republican-oriented Super PACs brought in about $230 million while Democratic-leaning super PACs raised less than $80 million.

Chart 1. Contributions to Super PACs by political allegiance

Super PACs do not officially declare their allegiance to any political parties, and some, like The Campaign for Primary Accountability claim to be non-partisan. The analysis instead is based on Sunlight researchers' categorization of Super PACs by political orientation, which disregarded those that didn't neatly fit within party labels. For more, read the methodology or see the "political orientation" column in a downloadable .csv file summarizing super PACs financials. Summary details are posted on the Super PAC spending and fundraising by political leaning page, which includes detailed charts comparing the month-by-month party dynamics of contributions, expenditures, primary election spending, general election spending, and general election presidential spending.

Table 1. Total ending cash balance, spending and itemized contributions by reporting period

The dynamics of raising–and spending–money are quite different: Republicans gave freely in a fiercely-fought Presidential primary, while Democratic mega-donors largely stayed on the sidelines. As a result, GOP-leaning Super PACs outspent their Democratic rivals in all races $103 million to $13 million–roughly 8-1. Yet despite being outspent by $90 million in the primary, Democratic super PAC's have little to show for it: GOP Super PACs had more than $79 million in the bank on June 30, while liberal Super PAC's had less than $26 million.

Chart 2. Super PAC independent expenditures by political allegiance, though July 22

Democratic super PACs may have been greatly outspent so far but their Republican-aligned rivals spent the largest share of their money attacking other GOP primary candidates. Through July 22, GOP Super PACs had spent almost $124 million–but about $60 million of that went to negative ads about other Republicans. In contrast, just $18.6 million went to negative ads about Democrats ($45.5 million went to ads supporting Republicans). Those numbers, however, probably underestimate the amount of negative advertising against Republicans; during the primary it wasn't uncommon for Super PAC's to describe postive ads as "also opposing" their rivals in campaign finance filings.

In contrast, Democratic-leaning Super PAC's have spent $21 million opposing Republicans (primarily Mitt Romney) and less than $600,000 opposing other Democrats.

Lindsay Young also contributed research to this report.