Speaking in his most closely watched speech of the year, Jerome H. Powell, the chair of the Federal Reserve, clearly signaled that the central bank was poised to cut interest rates in September.

And while Mr. Powell stopped short of giving a clear hint at just how large that move might be, he forcefully underscored that the central bank stands prepared to adjust policy to protect the job market from weakening further and to keep the economy on a path for a soft landing.

“The time has come for policy to adjust,” Mr. Powell said during the Kansas City Fed’s annual conference at Jackson Hole in Wyoming. “The direction of travel is clear, and the timing and pace of rate cuts will depend on incoming data, the evolving outlook, and the balance of risks.”

He then added: “We will do everything we can to support a strong labor market as we make further progress toward price stability.”

Mr. Powell’s speech — his firmest declaration yet that the Fed is pivoting its stance on policy — comes as the central bank approaches a critical juncture. After more than a year of holding interest rates at 5.3 percent, the highest level in two decades, investors widely expect officials to cut them at their Sept. 17-18 meeting.

Policymakers have been using high rates to try to cool the economy and, by doing so, wrestle down rapid inflation. But with price increases now slowing substantially and the job market showing signs of pulling back, officials have been indicating that they are preparing to begin dialing back the pressure.