None of these groups have to adhere to contribution limits and the elite donors who contribute to them often prove highly influential.
The majority held today that the strictest judicial scrutiny need not apply to contribution limits.
Legal and legislative challenges to contribution limits are already proliferating at the state level and federally.
PMA and its employees have given $58,600 to Mr. Murtha's campaign since 2005, according to contribution records.
The primary issue is whether 527 committees should be regulated the same way as other political groups, which are subject to contribution limits and other campaign finance restrictions.
But drafters of the measure did not follow the models when it came to contribution levels or deadlines for fund-raising.
The proposal, which would have allowed the donors to spend money on political advertising without being subject to contribution limits, was not approved.
Unlike other donations to parties, soft money is not subject to contribution limits, allowing wealthy individuals and corporations who have already given the maximum under the finance limits to give more.
The core of the issue is whether 527 and 501(c) groups should have to register with the commission as political committees, a change that would subject them to contribution limits and other restrictions.
The draft the commission passed is far less ambitious than others it considered, some of which would have required the 527 groups to register as political committees with the commission and submit to contribution limits and other regulations.
"Candidates and parties are being disadvantaged by the fact that individuals and corporations can give unlimited money to 'super PACs,' " he said, referring to committees that make only independent expenditures and are not subject to contribution limits.
