The Treasury Department had issued a statement on Sunday saying banks have adequate liquidity for lending, surprising investors who did not know that might be an issue.

The moves intensified concerns about the Trump administration’s economic policies, in the wake of a Bloomberg News report that the president had discussed firing Powell.

Asked on Tuesday whether he also had confidence in Powell, Trump said the Federal Reserve is raising rates “because they think the economy is so good.”

Even so, Trump’s frustration with Powell over the market’s performance – expressed in tweets and interviews – may turn to his Treasury chief, who recommended Powell’s nomination.

Before Tuesday’s comments, one person familiar with the president’s thinking said that Trump had weighed dismissing Mnuchin, while another said that his tenure may depend in part on how much markets continue to drop.

Since taking office, Trump has looked to the stock market as a benchmark for his presidency, yet much of the gains in equities since his election have been erased by months of turmoil, as investors grow increasingly concerned about the impact of the administration’s trade battles with China and Europe.

After Mnuchin’s call on Monday – which produced no public statement – stocks continued their Christmas Eve slide, ending the day with the benchmark Standard & Poor's 500, down 2.7 per cent, hitting its lowest level in 20 months.

The president has acknowledged that he cannot fire Powell, raising speculation he may target Mnuchin.

“There are plenty of people inside the White House who are not fans of Mnuchin, who are happy to throw him under the bus,” said Stephen Myrow, managing partner at Beacon Policy Advisors in Washington and a former Treasury official.

“Up ’til now, he’s been protected by the fact that Trump liked him and he’s been a loyalist.”

In a sign Trump may have lost some faith in Mnuchin, the president has asked whether one or more of his advisers could meet with Powell, according to a person familiar with the matter.

That would be seen as undermining the authority of the Treasury chief, who sees Powell for lunch once a week and is normally the official designated to deliver the administration’s views.

Investors have many reasons to worry as Trump’s trade war with China is creating uncertainty for businesses.

A partial government shutdown this week is raising concerns about Washington’s ability to find bipartisan solutions to pressing problems, and the president’s musings about firing Powell, and the abrupt departure of Defence Secretary James Mattis, have added to the sense of turbulence.

“The financial markets need certainty, and a Federal Reserve that can independently set monetary policy,” said representative Maxine Waters, a California Democrat and the incoming chairwoman of the House Financial Services Committee on Monday.

“The recent actions of the president and the Treasury secretary, however, have been erratic and are creating uncertainty and instability in the markets.”

While Trump regularly took credit for the stock market’s rise, he has consistently pointed elsewhere to explain its decline.

Unlike others Trump has cut loose, the president has a long relationship with Mnuchin, 56, a former Goldman Sachs partner and film financier who served as Trump’s chief campaign fundraiser.

But Mnuchin’s standing with Trump may be undermined by moves that risk his reputation on Wall Street, a Treasury secretary’s stock in trade.

Last week in an interview with Bloomberg News, Mnuchin pointed to long-standing phenomena to explain the stock market’s recently volatility.

He cited five-year-old restrictions on banks using their own capital to make speculative market bets, known as the Volcker Rule. He also mentioned high-frequency trading, an industry practice that has been common for more than a decade.

On Sunday, Mnuchin announced that he had called the six largest US banks and was reassured they have “ample liquidity available for lending.”

“I don’t know anybody who thought before last night that banks were suffering from lack of liquidity,” Roberto Perli, a partner with Cornerstone Macro LLC, wrote in an analysis on Monday.

“Even the Fed and other agencies are very satisfied with the health of the banking system, to the point of relaxing a bit the regulatory grip.”

The move “smacks of desperation and nervousness,” said Paresh Upadhyaya, a portfolio manager at Amundi Pioneer Asset Management in Boston.

Then on Monday, Mnuchin held the hastily organised call with the President’s Working Group, a list of top US financial regulators, who assured him they are seeing nothing out of the ordinary in markets.

Holding what seemed like an emergency discussion with financial regulators on a day when markets closed early for the Christmas holiday may have only added to investor anxiety.

Mnuchin did not clear either move in advance with Trump, according to an administration official, who said the Treasury secretary acted under his normal authority.

Publicly, the president lashed out on Monday at the Federal Reserve as “the only problem our economy has” because it keeps raising interest rates.

Over the weekend, Mnuchin sought to reassure financial markets that Powell’s job is safe after the report on Friday that Trump had consulted advisers many times in the previous few days about firing Powell.

Mnuchin tweeted that Trump told him he did not even have the authority to remove the central bank chief, a message that an administration official confirmed the president had authorised.