Millions of Americans struggling to save for retirement, or trying to live off their investments in old age, are hobbled each year by high fees on products recommended by financial advisers. Now, with Donald Trump’s election, a bitterly debated regulation that requires advisers to put their clients’ interests first could be derailed.

The Department of Labor ruling, set to take effect in April, was pushed by President Obama and resisted by Wall Street for five years before it was established this spring. Trump hasn’t specifically referred to the regulation, known as the fiduciary rule, but unwinding what he argues is regulatory red tape was central to his campaign, and his adviser Anthony Scaramucci, founder of SkyBridge Capital, has argued that the rule should be revoked.

“It’s a bad regulation that will kill jobs and hurt the very investors it purports to protect,” Scaramucci said. “It should be scrapped or defanged.”

Scaramucci’s committee on Trump’s transition team will influence who is named to lead the Securities and Exchange Commission and other financial overseers. For Treasury secretary, Trump has named Steven Mnuchin, a veteran of Goldman Sachs.

With compliance set to begin in April, “a new labor secretary probably will delay the regulation,” said Nathan R. Dean, government analyst for Bloomberg Intelligence. Although Trump can’t immediately dismantle the ruling, “he can ensure it’s weakened,” Dean said.

In addition to requiring that investment recommendations be in the client’s best interest, the fiduciary rule says brokers, retirement-investment advisers, and insurers must inform clients about the products’ fees and commissions.

The rule was opposed by Republicans leading Congress and many Wall Street and insurance companies, who have said its increased compliance costs will make it too expensive for financial service companies to manage money for low-income people with smaller accounts.