$55 million for conservative campaigns — but where did it come from?

$55 million for conservative campaigns — but where did it come from?

WASHINGTON â€" The financial firepower that fueled the rise of a network of conservative advocacy groups now pummeling Democrats with television ads can be traced, in part, to Box 72465 in the Boulder Hills post office, on a desert road on the northern outskirts of Phoenix.

That's the address for the Center to Protect Patient Rights, an organization with ties to Charles and David H. Koch, the billionaire brothers who bankroll a number of conservative organizations.

During the 2010 midterm election, the center sent more than $55 million to 26 GOP-allied groups, tax filings show, funding opaque outfits such as American Future Fund, 60 Plus and Americans for Job Security that were behind a coordinated campaign against Democratic congressional candidates.

INTERACTIVE: The money behind the air war

The money from the center provided a sizable share of the war chest for those attacks, which included mailers in California, robo-calls in Florida and TV ads that inundated a pocket of northeastern Iowa. The organizations it financed poured at least $46 million into election-related communications in the 2010 cycle, among other expenditures.

In that campaign, outside groups â€" the vast majority backing Republicans â€" reported spending a record $304 million, according to the nonpartisan Center for Responsive Politics. Democratic-allied groups are still trying to match their success.

With such spending set to reach unprecedented levels in the 2012 election, the activities of the Center to Protect Patient Rights â€" whose existence was first reported this month by the Center for Responsive Politics â€" provide a glimpse into the network of deep-pocketed conservative advocacy groups that have already begun an air war against President Obama.

SPREADSHEET: Center to Protect Patient Rights grantees

Because these nonprofit groups are under no obligation to reveal their donors, the sources of their funding has remained a mystery.

The Koch brothers, with a combined net worth estimated by Forbes at $50 billion, are thought to be among the most generous backers of the efforts on the right. They have supported Americans for Prosperity, which, together with its sister foundation, plans to spend $151 million in the 2012 election.

Exactly how the Kochs and their allies are directing their sizable resources is unknown. But an examination of the Center to Protect Patient Rights provides some important clues.

The Kochs have several ties to the center. It is run by Sean Noble, a Phoenix-based GOP consultant who is a key operative in the Kochs' political activities, as first noted by the investigative blog Republic Report. One of the center's original directors, Heather Higgins, is chairwoman of the Independent Women's Forum, which has received funding from a Koch-controlled foundation. And Cheryl Hillen, a Connecticut-based consultant who raised $2.6 million for the center, was director of fundraising for the Koch-backed Citizens for a Sound Economy.

Koch spokeswoman Melissa Cohlmia directed questions to the center, declining to say whether the Kochs were involved.

"Koch respects the lawful right of this organization, and others like it, to protect their privacy," she said in an emailed statement.

The center was largely used as a vehicle to pass millions to other organizations, which also zealously guard the anonymity of their donors. Some campaign finance experts suggested the center could have been set up to pool money from various sources.

"Rather than have to make the decision yourself, you would entrust them to spread it around," said Ellen P. Aprill, a tax law professor at Loyola Law School.

The center's plans for 2012 are unknown. But in March, Noble filed paperwork expanding its advocacy beyond patient rights to include "limited government and free enterprise."

Aside from its ties to the Kochs, there is scant evidence of who is behind the group. And no one involved would talk about it.

Noble did not respond to repeated phone calls and emails. Courtney Koshar, a Phoenix anesthesiologist and the organization's only other director, did not respond to requests for comment. And a Phoenix doctor who once sat on its board said he couldn't remember who asked him to join.