The Federal Reserve left interest rates unchanged Wednesday, a widely expected move as the U.S. economy continues to grow at a slow and steady pace.

But central bank officials are monitoring a number of risks, including ongoing trade tensions and the coronavirus outbreak in China that has many government executives, public health officials and business leaders on edge.

“We expect moderate economic growth to continue,” Fed Chair Jerome H. Powell told reporters Wednesday. But “uncertainties about the outlook remain, including those posed by the new coronavirus.”

Powell said it was too early to tell what the impact of the coronavirus would be on China’s economy or any other part of the world. The coronavirus has killed more than 100 people and led airlines and other businesses to rapidly halt operations.

“The situation is really in its early stages, and it is very uncertain about how far it will spread and what the macroeconomic effects will be," he said. "I’m not going to speculate about it at this point ... We are very carefully monitoring the situation.”

The Fed’s interest rate remains in a range of 1.5 to 1.75 percent, a low level by historical standards that is meant to give a modest boost to the economy by encouraging more lending and home-buying. The Fed lowered interest rates three times last year, taking the rate down from a post-recession high of nearly 2.5 percent.

“Many, many people benefit from low interest rates,” Powell said when he was asked about savers getting hurt by such low rates. As he travels around the country, he said, many low and moderate-income people tell him, “Do whatever you can to keep this expansion going."

The Fed painted a mostly upbeat picture Wednesday of a U.S. economy that is growing and creating job opportunities for Americans who struggled for years to find employment. Fears of a U.S. recession this year have largely faded since the Fed began cutting rates in July. President Trump’s partial trade deal with China has also helped calm anxieties on Wall Street and among business leaders.

“The bottom line from Powell is the Fed is still focused on keeping the recovery on track,” said Julia Coronado, head of MacroPolicy Perspectives and a former Fed economist.

But the Fed notably downgraded the language it uses to describe consumer spending, which accounts for 70 percent of the economy.

“Household spending has been rising at a moderate pace,” the Fed wrote Wednesday in a statement. Last year, the Fed described consumer spending as “strong.”

Fed leaders do not anticipate moving interest rates up or down at all in 2020, but Wall Street is predicting at least one cut, probably in July or September. Powell has said it would take a “material reassessment” of the economy’s health for the central bank to alter rates.

Beyond interest rates, many investors are paying close attention to Powell’s plans for the Fed’s $4.1 trillion in assets, a total that has been growing again in recent months.

The Fed has been buying a substantial amount of Treasury bills since September, which some argue has propped up the stock market. The S&P 500 Standard & Poor’s 500-stock index has risen about 10 percent since the Fed announced in October that it would buy more T-bills. Fed leaders insist these are merely technical adjustments to the central bank’s plumbing.

“Our Treasury bill purchases should not be confused with the large-scale asset purchase programs that we deployed after the financial crisis,” Powell said in October.

This week Powell said the Fed will ensure there is “ample” money in the financial system, and the balance sheet is likely to keep expanding through the second quarter, which ends in June.

“The Fed’s balance sheet expansion seems on autopilot through at least April,” said Peter Boockvar, chief investment officer at Bleakley Advisory Group.

The Fed held about $4.5 trillion in assets in 2017 — mostly U.S. government bonds and mortgage-backed securities — as part of its efforts to stimulate the economy and keep interest rates low. But the Fed shed roughly $700 billion from mid-2017 through mid-2019. Banks grew worried that there was not enough liquidity in the system, especially cash “reserves” on hand at the Fed.

Since September, the Fed has bought about $400 billion worth of short-term Treasury bills to ensure there is enough money in the system to keep overnight borrowing rates for banks where the Fed wants them.

“This is a one-time thing we are doing to adjust the level of reserves so money markets can operate smoothly on an ongoing basis," Powell said.

But there is still the overhanging question of what happens after the spring. Powell said that the Fed will provide more details soon but that final decisions had not been made yet. Some predict a nasty market reaction when the Fed stops buying T-bills.

“This is tricky terrain for Powell and if mishandled could be disruptive,” Krishna Guha, vice chair of the Evercore ISI research group, wrote in a note to clients this week.

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