After Monday’s tumble, Mr. Trump’s aides were left in the awkward position of ignoring it or explaining that it was not especially meaningful. Treasury Secretary Steven Mnuchin, who accompanied Mr. Trump to Ohio, declined to comment on the market when he encountered reporters on Air Force One during the trip back to Washington and again on the tarmac after it landed. The television on the plane was tuned to Fox Business Network as it dissected the day’s dark developments.

“Look, markets do fluctuate in the short term. We all know that,” Raj Shah, a White House spokesman, told reporters en route to Ohio when the market was heading down. “And they do that for number of reasons. But the fundamentals of this economy are very strong and they’re headed in the right direction — for the middle class, in particular.”

After the president returned to the White House, his press secretary, Sarah Huckabee Sanders, issued a written statement.

“The president’s focus is on our long-term economic fundamentals, which remain exceptionally strong, with strengthening U.S. economic growth, historically low unemployment and increasing wages for American workers,” she said. “The president’s tax cuts and regulatory reforms will further enhance the U.S. economy and continue to increase prosperity for the American people.”

Those tax cuts may actually be contributing to the market’s decline. Analysts attributed plummeting share prices to Friday’s job report, which showed wages beginning to rise as the economy nears full employment. Rising wages are a good thing for those who receive them, and for the presidents who seek to stimulate them, but investors see them as a sign of possible inflation and higher interest rates.

Mr. Trump pushed through a $1.5 trillion tax cut plan in December to fuel faster growth despite warnings from economists that the economy did not need the help. The economy is growing slowly by historical standards, but the low level of unemployment suggests that it is also growing about as fast as it can.

Instead of fueling growth, investors worry that the extra money Mr. Trump is pumping into the economy through tax cuts and, if he is successful, with a $1.5 trillion infrastructure plan will inflate wages and prices. And that could prompt the Federal Reserve to raise interest rates more quickly, suppressing growth to keep a lid on inflation.