Securities and Exchange Commission Chairman Gary Gensler called for an aggressive approach to policing cryptocurrency as the industry’s surging growth has rattled the financial world and sparked a debate over how hands-on Washington regulators should be in shaping its future.

Gensler, testifying Tuesday before the Senate Banking Committee, argued the vast majority of digital assets traded over crypto exchanges need to register with the SEC so the agency can protect investors against abuses.

“It’s a highly speculative asset class,” Gensler said, expressing skepticism about claims by crypto advocates that it offers a path to financial independence for smaller investors.

Coinbase, the nation’s largest cryptocurrency exchange, revealed last week that the SEC has threatened to sue if it moves forward with a program that would allow investors in digital assets to earn interest on their holdings. In his testimony, Gensler noted the company hasn’t yet registered with the Wall Street regulator, “even though they have dozens of tokens that may be securities.”

Coinbase CEO Brian Armstrong criticized the SEC’s crackdown as “sketchy,” and some Senate Republicans echoed the rebuke, arguing to Gensler his agency needs to develop clearer standards.

Sen. Patrick J. Toomey (R-Pa.), the top Republican on the Senate banking panel, said Gensler’s approach so far has been “regulation by enforcement, and it’s very objectionable.”

Gensler responded that the SEC is following standards established by Congress and the courts. “You’ll find I’m not negative or a minimalist about crypto,” he said. “I just think it would be best if it’s inside the investor protection regime that Congress laid out.”

Gensler’s appearance came five months into his tenure atop the SEC. He laid out the ambitious agenda he is pursuing to apply tough new standards to far-flung corners of the financial industry following years of Trump-era deregulation.

Among his priorities, Gensler highlighted efforts to force public companies to disclose more about their climate risks, executive compensation and the makeup of their workforces; apply stricter oversight to Chinese companies listing on U.S. exchanges; and foster more competition among the firms that execute trades for retail investors, an issue that grabbed headlines earlier this year around the explosion of “meme-stocks.”

The SEC chairman made an appeal for more staff as the agency attempts to tackle a sprawling to-do list. “We could use a lot more people,” he said, noting the agency’s head count has dropped 4 percent over the past five years.