A rotating cast of top candidates has roiled Polymarket betting on the next chair of the Federal Reserve, but the new favorite, BlackRock's Rick Rieder, has argued that bitcoin will replace gold and has recommended people should have it in their portfolios.

Rieder, BlackRock's chief investment officer for global fixed income, has rocketed to the top of the list of President Donald Trump's likely picks in the prediction markets, and he's frequently waxed supportive of cryptocurrencies.

He said as far back as 2020 — in much earlier days of digital assets — that bitcoin would take over for gold as a store of value, "because it’s so much more functional than passing a bar of gold around," he said in a CNBC interview. And more recently, he told the same outlet that bitcoin should be part of a smart investment mix, saying that the leading digital token and gold were "things that give you a little bit of ballast in the portfolio."

In that September interview, when bitcoin was still above $112,000, he predicted "it's going to go up." The cryptocurrency is currently trading around $88,000, having fallen recently on possible tariffs and other geopolitical turmoil.

Trump has a choice to make before the term of Fed Chairman Jerome Powell — who the president has framed as his economic nemesis — is set to expire on May 15. It was Trump who originally placed Powell, a Republican, in that pivotal role, but the president has since routinely lamented his performance, calling him "dumb" and "stupid" and nicknames such as "Mr. Too Late."

Meanwhile, Trump has often teased about frontrunners for his replacement, making for a volatile prediction market. Rieder has said it's "an unbelievably honor to even be mentioned in that list."

Rieder vocally shares Trump's frustrations at the sedate pace at which the Fed has cut interest rates. In a recent interview during the president's trip to Davos in Switzerland, Trump called Rieder "very impressive," and his odds on Polymarket have climbed from under 3% to almost 53% at their height, before settling at a current 48%.

For the crypto sector, a Fed chair can pull multiple levers. Apart from a heavy influence in the group that sets the federal funds rate, the chair controls the board's regulatory agenda. However, Powell has deferred to the vice chair for supervision, Michelle Bowman, on the Fed's supervisory work.

So Rieder's crypto enthusiasm may not have a significant play in the rules the regulatory side of the Fed writes for such things as stablecoins or central bank digital currencies (CBDCs).

More than as a mechanic of policy, a Fed chair has a softer role as an outsized voice on the health and direction of the U.S. economy, and a staunch bitcoin advocate in that position would be a first.

Though Powell is departing soon as chairman, his term as a regular governor on the Fed board continues, leaving some question about whether he'll take the traditional route and exit after his leadership expires or stay on another two years. Every member of the board has an automatic seat on the Federal Open Market Committee that decides U.S. interest rates, meaning a Powell decision to stay would keep his generally centrist position in place in that group and would fail to open another seat for a Trump appointee.

Trump's relentless criticism of Powell escalated last month when his Department of Justice said it's investigating the central bank chairman for his public descriptions of renovations at the Federal Reserve buildings in Washington. Powell released an unusual, direct response.

"The threat of criminal charges is a consequence of the Federal Reserve setting interest rates based on our best assessment of what will serve the public, rather than following the preferences of the president," Powell said.