(CNN) President Donald Trump's frustration with Treasury Secretary Steven Mnuchin is ratcheting up further after markets suffered their worst Christmas Eve drop ever following Mnuchin's attempts to calm Wall Street failed, according to a source close to the White House.

The source told CNN that Mnuchin could be in "serious jeopardy" with Trump, who regularly rages at Cabinet members he feels have made mistakes before he cools off.

Trump nevertheless vouched for Mnuchin publicly, shifting blame for the market volatility to the Federal Reserve instead.

"Yes, I do," Trump said Tuesday when asked whether he had confidence in Mnuchin. "Very talented, very smart person."

But the source painted a different picture of Mnuchin's standing behind the scenes.

"Mnuchin is under the gun," the source said.

The Treasury secretary left Washington for a Christmas holiday in Mexico's Cabo San Lucas as the federal government shut down over the weekend, while Trump canceled his own planned trip to his Mar-a-Lago resort in Florida and remained cooped up in the White House over the holiday, absorbing a flood of negative news about the markets.

Trump could meet with Federal Reserve Chairman Jerome Powell in the new year, a person familiar with the matter told CNN Wednesday morning. Trump has fumed at Powell for raising interest rates, which Trump believes is driving the stock market lower. Some of the President's aides believe a face-to-face meeting could help ease tensions and allow the two men to discuss the underlying economy.

Mnuchin meets regularly with Powell and it's not unheard of for a Fed chair to meet with the President, though it's rare since the position is meant to be independent of politics.

Nothing has been formally scheduled. The Wall Street Journal first reported the discussions about the meeting.

At the same time in Washington, Mnuchin aides have been scrambling to find economic data to help their boss calm Trump down, but Trump was said to be unhappy with what Mnuchin was telling him, this source said.

An administration source dismissed the latest round of rumors that the secretary's continued tenure was on the line.

"This is nonsense," they said.

Over the weekend, the secretary spoke by phone with the President several times, including after a brutal trading day on Christmas Eve resulting in a 653-point drop in the Dow Jones Industrial Average, according to the administration source. The two men spoke on a variety of issues, including the government shutdown and an update on the status of trade talks.

Mnuchin, a former investment banker and film financier, has long been one of Trump's closest advisers, dating back to his time working with Trump on the 2016 presidential campaign. Still, sources have previously told CNN that Trump was upset with Mnuchin over his advice to appoint Powell as Federal Reserve chairman. Trump has criticized Powell and the Fed for increasing interest rates, subjecting Powell to the kind of scathing public critique that is common for senior Trump appointees but which threatens the political independence of the worlds most powerful central bank.

Wall Street has been exceptionally volatile all December, with investors already jumpy about signs of a global slowdown repeatedly spooked by Trump's own comments. The slide started in earnest with the President's own tweets following his announcement of a trade deal with Beijing, in which he suggested he may yet impose radically higher tariffs if he's not happy with negotiations.

Mnuchin turned heads in Washington and Wall Street with his attempts to calm the markets over the weekend in an attempt to head off a plunge.

Mnuchin tweeted on Saturday that he had spoken with Trump and issued a quote that he attributed to the President denying Trump had suggested firing Powell. Two sources previously told CNN that Trump had begun polling advisers on whether he has the legal authority to fire Powell.

Mnuchin then spoke with the heads of major US banks on Sunday and issued a statement that evening saying the banks had "ample liquidity."

But his efforts to calm markets that have been volatile for weeks appeared to fail on Monday.

The Dow dropped by 2.9% and the S&P 500 fell 2.7%, the biggest drops ever for the two indexes on Christmas Eve. That same day, Trump fired off a series of tweets, including one attacking the Federal Reserve.

On Christmas Day, Trump said he remained confident in Mnuchin but was still unhappy with the Fed.

"They're raising interest rates too fast," Trump said of the central bank.