"Slapping the acronym "JOBS" on the bill does not mask the damage this legislation will produce. If you bow to political pressure of the worst kind and sign this bill into law, the beacon of hope that many Americans have been waiting for in the past three years will be further dimmed."

Republicans and many Democrats — and the White House — have supported the bill as a way to help small companies go public more quickly, and raise capital in new ways. The legislation easily passed the House, with only a few dozen in opposition, and passed the Senate 73-26.

But Nader warned of several problems with the bill, including that the effort to help small companies is belied by the bill itself, which he said can help companies that make up to $1 billion in revenues. "Companies that reach revenues of this size are not small businesses," he wrote.

Nader also argued that companies will likely use accounting gimmicks to help keep their apparent size below the thresholds under the bill, and said language meant to make it easier to invest in small companies could end up burning small investors.

"The "JOBS" Act would allow these risky companies to launch without proper regulator's safeguarding," he wrote. "It would eliminate much of the personnel and financial disclosure for these start-ups that is typically in place to protect investors and consumers."