In a separate line of question, Rep. Huizenga's claim was supported by testimony from Jerome Lombard, president of the private client group at Janney Montgomery Scott LLC.

Lombard said the average annual charge on fee-based advisory accounts at his firm is nearly double the 0.59 percent average cost on commission-based brokerage accounts.

He also testified that up to 10,000 accounts with the firm, or one in eight clients, will be relegated to “no-advice service desk” by the end of the year, because they are too small to warrant the cost of servicing under the fiduciary rule's prohibited transaction exemptions.

“How that is in these clients best interest I will never understand,” said Lombard, who called for the rule's January 1, 2018 compliance date to be delayed at a minimum, and reiterated calls from other witnesses and lawmakers for the Securities and Exchange Commission to craft a new fiduciary rule.

David Knoch, president of 1^st Global, a Dallas-based advisory firms that specializes in partnering with CPAs around the country, testified that small investors are already losing access to commission-based IRA accounts.

Moreover, direct business accounts, where investors purchase mutual funds directly from investment management firms for a commission, have dropped 10 percent this year and are expected to drop another one-third by the end of the year.

But the rule's most dramatic impact so far has been with small business owners, according to Knoch, who testified that Simple IRA accounts serviced by his firm are down 20 percent in 2016, and are expected to drop another 40 percent by the end of 2018.

He said the rule fails to account for a 2011 study by the Labor Department that estimated losses of $114 billion annually to investors' lack of access to advice, calling that the “single biggest flaw” in the Department's calculations behind the rule.

Mark Halloran, senior director and head of regulatory strategy at Transamerica, testified that the rule is skewed against annuity products, and that small investors are already not receiving advice on annuities as a result of the rule.

The rule's preference for fee-based advisory costs is projected to cost investors, said Douglas Holtz-Eakin, president of the American Action Forum, a conservative think tank.

About three-quarters of IRA accounts hold less than $100,000 and are mostly in commission-based accounts. Transitioning to fee-based advisory accounts will result in an average of $800 a year in increased costs, and $1,500 in average annual duplicative fees for accounts charged a fee that have already paid commissions on mutual funds. “The fee-based world is much more expensive,” said Holtz-Eakin.

The lone witness supporting the full implementation of the fiduciary rule was Cristina Firvida, director of financial security and consumer affairs for AARP.

Repealing the rule would be costly for retirement savers, testified Firvida. And replacing it with a disclosure-driven alternative, such as the one advanced in a discussion draft by Rep. Ann Wager, R-MO, at the hearing, would not provide enough protection for investors.

“The rule has resulted in lower fees and better advice,” said Firvida. “Disclosure alone is not enough,” she said of Wagner's bill, which, unlike the fiduciary rule, does not specify how conflicts should be managed.