The U.S. Chamber of Commerce spent $13.8 million lobbying Congress and federal agencies in the first three months of 2015 -- more money than any other company or organization and nearly as much as the next two finishers combined. Google Inc., General Electric Company and the American Medical Association also ranked among the top 10 spenders.

The nation's top lobbying organizations and companies represent the interests of the pharmaceutical industry, medical groups and electric utilities. Altogether, the groups have spent $64 million on lobbying in 2015 alone. 

These 10 companies and organizations contributed the most money to Congress and federal agencies in the first quarter of 2015, according to data compiled by MapLight:

  1. U.S. Chamber of Commerce, $13.8 million
  2. National Association of Realtors, $7.7 million
  3. American Medical Association, $6.72 million
  4. U.S. Chamber Institute for Legal Reform, $5.72 million
  5. Google Inc., $5.47 million
  6. Pharmaceutical Research and Manufacturers of America, $5.44 million
  7. General Electric Company, $4.75 million
  8. National Association of Broadcasters, $4.72 million
  9. American Electric Power Company Inc., $4.69 million
  10. American Hospital Association, $4.63 million