The U.S. Chamber of Commerce said Thursday it is concerned a fiduciary rule being developed for advisors to retirement plans such as 401(k)s and IRAs may not promote the twin objectives of investor protection and investor choice.

“We are troubled by the possibility of a rule with an overly broad application … a rigid one-size-fits-all regulatory approach that will make it harder to serve current investors, particularly in small accounts,” Chamber Center for Capital Markets Competitiveness President David Hirschmann said in a letter to Labor Department Secretary Thomas Perez.

He said he is concerned the rule would have very little leeway and make it harder than usual for advisors to get exemptions from DOL requirements.

In another argument against a stiff fiduciary rule, Hirschmann noted the Securities and Exchange Commission, the Financial Industry Regulatory Authority and other regulators have already expanded robust protections for retirement savers.