“Do the president and I think a lot alike on a lot of things? Absolutely. That’s one of the reasons he picked me to be an economic adviser and be on the Fed, because we share a lot of the same economic philosophy,” Mr. Moore said. But “I don’t think anybody can reasonably say I am a sycophant for Trump, because I’m not.”

The Fed has abruptly halted what had been a steady campaign of interest rate increases, going back to 2017. At its most recent meeting, officials indicated they expected not to raise rates this year, and they revised down their estimates of economic growth for 2019 amid signs of global weakness. Mr. Powell told reporters that, depending on how economic data played out, the Fed’s next move could just as easily be a rate cut as a rate increase.

Mr. Moore has been pushing for the Fed to go further and adopt a rule in which it adjusts interest rates in response to price swings in a wide array of commodities, like oil, metals and agricultural products. In early March, he emailed a New York Times reporter, urging an article on the idea that the Fed had driven commodity prices down with its rate increases, acting as a “wet blanket” on economic growth. He said Mr. Trump agreed with his assessment that the Fed was keeping the economy from growing as fast as 4 percent per year.

A week later, Mr. Moore laid out the commodity targeting plan on the opinion pages of The Wall Street Journal, his former employer. When commodity prices rise, the Fed would raise interest rates to prevent inflation, Mr. Moore and his co-author, Louis Woodhill argued, and it would reduce rates when commodity prices fall. Mr. Trump saw the piece, and he offered Mr. Moore the Fed post, which Mr. Moore said he had never previously considered.

“I never really thought about this, but, you know, I thought that — the more I thought about it, the more I thought this is economic policy right on the front line,” Mr. Moore said. “That’s what I do. I thought this would be an amazing experience, and hopefully I could work with Powell to get him shifted over to a more pro-growth” policy.

“I would use commodity prices as a guide,” Mr. Moore added. “I wouldn’t be doctrinaire about it.”

Few economists subscribe to that theory, which is in many ways the opposite of what the Fed does today, by focusing on a measure of “core” inflation that strips out energy and food prices. They warn that targeting commodity prices could trigger interest rate increases at inopportune times. For example, commodity prices were soaring in the middle of 2008 when the recession was already underway. If the Fed had responded according to Mr. Moore’s prescription and raised rates, that crisis would almost surely have been worse.

The same could be said for 2010 and 2011, when growth was lackluster and unemployment near double digits but commodity prices had rebounded from crisis-era lows. The Fed nurtured the recovery with near-zero interest rates and large-scale purchases of government-backed securities. But the commodity-focused approach would have implied higher rates and could well have stopped the expansion in its tracks.