Officials with one of Washington's most powerful special interests gave half a million dollars to a Democrat-aligned non-profit group that mainly consists of a mailbox in a UPS store in the nation's capitol.

The $500,000 came from the Pharmaceutical Research and Manufacturers Association (PhRMA) to Montana Browth, according to the Center for Public Integrity's Michael Beckel.

"Little is known about the group, but Internal Revenue Service documents indicate that the drug lobby's contribution supplied the bulk of its funding," Beckel reports. He said Montana Growth raised more than $816,000 during 2011.

"Its expenses included $275,000 on 'grassroots and grasstops consulting' and $70,000 for research on 'important issues facing the state of Montana to [help] better inform advocacy efforts,'" Beckel said.

"It also transferred $40,000 to a liberal-leaning group called 'America Votes,' which like Montana Growth, is a 'social welfare' nonprofit under Section 501(c)(4) of the U.S. tax code. This year, America Votes reported spending about $47,000 to the Federal Election Commission for telephone calls supporting President Barack Obama and Sen. Bob Casey, D-Pa., in October," Beckel said.

Montana had one of the most fiercely contested Senate rates this year, pitting first-term incumbent Democrat Jon Tester against Republican Rep. Denny Rehberg. Despite substantial Rehberg leads at several points during the campaign, Tester won re-election by nearly four percent.

Beckel previously reported that PrHMA also gave big donations to other politically active non-profits, including:

* $750,000 to Freedom Path, which spent substantial sums encouraging Utah voters to re-elect Sen. Orrin Hatch.

* $264,500 to the American Legislative Exchange Council (ALEC), a controversial organization made up of state lawmakers and corporate executives that creates suggested model legislation for state legislatures.

* $250,000 to the liberal-aligned Citizens for Strength and Security.

* $200,000 to anti-tax crusader Grover Norquist's Americans for Tax Reform.

* $40,000 to conservative think tank the Heritage Foundation.

* $40,000 to the Utah Families Foundation, which, according to Beckel, Hatch helped start in the 1990s and continues to assist.