WASHINGTON — The Obama administration is unveiling rules that will require that brokers who recommend investments for retirement savers meet the stricter standard that now applies to investment advisers: They must act as “fiduciaries” — trustees legally obligated to put their clients’ best interests above all.

The action, in rules issued Wednesday by the Labor Department, could shake up how billions of dollars in Americans’ retirement investments are handled by brokers. The government action will put brokers — who sell stocks, bonds, annuities and other investments — under the stricter requirements that now apply to registered financial advisers.

The new rules were the target of heated lobbying campaigns mounted by both the financial industry and consumer advocates.

“This is a huge win for the middle class,” Labor Secretary Thomas Perez said Tuesday in a conference call with reporters. “We are putting in place a fundamental principle of consumer protection.”

The rules will be phased in starting a year from now. Full compliance will be required by January 2018.

The change could alter the types of investments a broker recommends for your retirement account. Their advice could move away from riskier investments. And a broker may have to tell you when they have a conflict of interest with regard to a financial product — like receiving fees — that could prevent them from putting your interest first in recommending it.