Answer
The sources of pressures are innumerable, but the most intense and continuous pressure to change or rather influence accounting principles or standards come from; Individual companies, CPAs and Accounting firms, AICPAs, academicians, investing public, financial community (analysts, bankers, etc) financial executive institutions, government (SEc, IRS among other agencies) and industry associations.
Work Step by Step
All these entities put pressure on the FASB so as to change existing rules and development of new ones. Its also logical to state that these sources also put pressure on FASB to change GAAP.
