Washington (CNN) Never shy about taking credit for the stock market when it soared, President Donald Trump has been characteristically quick to assign blame as Wall Street sputters.

Whipsaw markets and a string of steep dives have spawned a pervasive anxiety in the White House, according to senior officials, where for the past two years the strength of the US economy has provided steady reassurance amid even the deepest of political crises.

As Trump faces fresh vulnerability — most aspects of his life are now under investigation just as Democrats are preparing to assume control of the House — the economy no longer offers the same comfort it once did, despite rising wages and the lowest unemployment rate in half a century, according to interviews with multiple White House officials and people close to Trump.

The business cable networks that air silently on West Wing flat-screens have chronicled dismal losses on several days over the past weeks, each chipping away at what was once Trump's most reliable boast: record market highs. Wall Street rallied early Tuesday but ended with only modest gains, and the Dow and S&P 500 are still on track for their biggest December loss since the Great Depression

On afternoons when markets close down in the triple-digits, Trump wonders aloud whether his political standing will take a hit — and has been told by some advisers that it could. Most days he is kept regularly updated on the market fluctuations, either by senior advisers or through watching coverage on television.

One official said Trump has taken even more interest in the markets over the past several months, though he's always used Wall Street as a barometer of his success.

"It's his daily gut check," said one official, who declined to be named. "For him it's like an instant read, good or bad."

The volatility comes after several disappointments, including General Motors' decision last month to shutter plants in Ohio and Michigan -- a business move that struck deep in the heart of MAGA country, where Trump wooed voters away from Democrats with repeated pledges to bring back lost manufacturing jobs.

Trump's trade war with China has also generated mixed political results, with tariffs biting Trump's loyal base of farmers. The President, whose advisers promised him Wall Street would love a resolution with Beijing, has been irritated that markets instead tumbled after he revived the threat of escalated tariffs if the ongoing negotiations don't bear fruit.

And, most unhappily of all, the benefits of Trump's much-celebrated tax deal -- which never gained much traction with voters -- have faded. The massive tax cuts for corporations and individuals that Trump and his fellow Republicans heralded at this time last year have helped boost growth over the past 12 months, but also drove more than $1 trillion in stock buybacks that lined the pockets of shareholders rather than unleashing a spate of business investment to benefit workers.

Not all of the problems are at home, or even of Trump's making. Concerns about a weakening global economy helped drive Monday's sell-off, along with the expectation the Federal Reserve will defy Trump and again raise its benchmark interest rate this week.

But the protracted trade war Trump is waging with China, anxiety about political instability in Washington amid another round of shutdown talk and general concerns about the strength of the US economy are still underlying factors in the market zig-zags.

In public, Trump is still bullish on the US economy. He's likely to again proclaim American economic strength when he makes a return visit to the World Economic Forum in Davos, Switzerland, next month — the same venue he used early this year to tout protectionist policies he said were boosting the US, even as other economies struggle.

Since then, Trump has also used a humming economy to warn against steps that might short-circuit his ability to govern.

"It's hard to impeach somebody who hasn't done anything wrong and who's created the greatest economy in the history of our country," the President said last week in an interview with Reuters, a version of the argument against impeachment he's made repeatedly since the summer.

Still, a President who claims credit for a strong stock market may have a difficult time explaining why he doesn't deserve the blame when the bull turns bear.

And officials said privately Trump has expressed worry that some economists are now projecting a downturn in the next several years. Trump's own advisers have downplayed the possibility, but the President — who consumes information from a wide swath of sources, including television and a wide network of wealthy friends — has taken notice of the chatter.

It's led him to seek out opportunities to bolster Wall Street, including the tentative deal he struck with Chinese President Xi Jinping earlier this month in Argentina. But even that did little to stabilize markets; instead, a lack of detail and continued threat of tariffs caused further sell-offs.

That was the opposite of Trump's goal heading into the meeting. Ahead of the talks, held on the margins of the G20 in Argentina, Trump advisers like Treasury Secretary Steven Mnuchin and National Economic Council Director Larry Kudlow suggested striking a deal could reassure investors. According to people familiar with the matter, Trump complained when the advice didn't pan out.

He's taken to ranting against Jerome Powell, the Federal Reserve chairman he nominated a year ago but now resents, calling his decisions crazy and misguided. And he's complained about those advisers, like Mnuchin, who pushed him toward a chairman who has overseen a steady rise in interest rates and a tightening in monetary policy.

"I hope the people over at the Fed will read today's Wall Street Journal Editorial before they make yet another mistake," Trump wrote on Twitter Tuesday morning, a day ahead of another expected announcement from the Fed that it will raise its rates. "Feel the market, don't just go by meaningless numbers. Good luck!"

The editorial he cited was headlined "Time for a Fed Pause," and urged the body to "follow the signals that suggest a prudent pause in raising rates."

The Journal is hardly the only one advocating for such a respite. Several prominent economists say driving up borrowing costs for Americans could risk triggering another recession. But because Trump has defied tradition and applied pressure to the historically independent body to keep rates low, some analysts say Powell's options are limited.

"I'm in the peculiar position of thinking the Fed should not raise rates, but it should not listen to the President, which is a hard position," Nobel Prize-winning economist Paul Krugman said Monday on CNN's Quest Means Business. "There's a pretty good case for not raising rates now. But to not raise rates in this meeting would look like they're allowing themselves to be bullied."

Speaking at a White House briefing on Tuesday, press secretary Sarah Sanders insisted the President was well within bounds when he criticized the Fed chairman.

"The President is stating his opinion, which he is perfectly within his right to do so," she said. "I think that's one of the reasons people like him is because he does that and he does it regularly. He's been very clear about what his position is while at the same time he understands the Fed is an independent agency. It doesn't take away the President's right to state his opinion on a particular matter."