Janet Yellen is preparing to walk a tightrope.

When the Federal Reserve chair addresses lawmakers this week in Washington, she will have to strike a balance between sounding confident on the domestic economy and acknowledging increased risks from abroad. Two weeks after officials signaled interest rates may rise more slowly than previously expected, economists and investors will try to gauge Yellen’s willingness to delay tightening at the March meeting.

With financial market turmoil causing uncertainty about the outlook, energy prices damping inflation and the European Central Bank preparing a stimulus boost that may bolster the dollar, the market-implied probability for a rate increase next month has dropped to 2 percent from more than 50 percent at the start of the year. Policymakers including Vice Chairman Stanley Fischer have cautioned that it’s still too soon to decide the next step.

“I don’t think we should expect Yellen to throw the towel on a March hike,” said Thomas Costerg, a senior U.S. economist at Standard Chartered Bank in New York. “She may emphasize the positives in the U.S. economy, particularly the still-strong labor market. Looking ahead, she may sound more cautious, and she will likely highlight that the negatives are mostly from abroad and that they are watching the global picture closely.”

Yellen is scheduled to appear before the House Financial Services Committee at 10 a.m. Wednesday and will address the Senate Banking Committee the next day. She’ll have evidence to support the Fed’s view that the U.S. labor market remains solid and wages are showing signs of picking up.

The Fed raised interest rates in December for the first time in almost a decade. U.S. economic growth slowed in the fourth quarter as businesses cut back investment, raising concern that weakening global trade will damp or even interrupt one of the longest periods of continuous expansion since World War II. Oil prices are close to the lowest level since 2003.

At the heart of the concern about the world economy is China, where policymakers are battling the slowest growth in 25 years, the depreciation in the yuan to the lowest in five years and an equity selloff that shook global markets, tightening financial conditions from the United States to Europe. The Standard & Poor’s 500 Index is down almost 10 percent this year, while the Stoxx Europe 600 Index has lost about 14 percent.

“Yellen will acknowledge that the tightening in financial conditions since the December meeting could have a negative impact on the growth and inflation outlook,” said Steven Friedman, senior investment strategist at BNP Paribas Investment Partners in New York. “But so long as she continues to signal a bias to raise rates, her comments are unlikely to lead to a meaningful improvement in market sentiment.”

Fed officials including Fischer, Governor Lael Brainard and New York Fed chief William Dudley have cautioned that the impact of financial-market turbulence on the U.S. economy is still unclear and needs careful monitoring. Cleveland Fed President Loretta Mester said she continues to expect the U.S. economy to warrant gradual interest-rate increases.

Lindsey Piegza, chief economist at Stifel Nicolaus & Co., said Yellen will use her congressional testimonies to defend the December liftoff and keep options open for March.

“I think she’ll dig in her heels,” Piegza said. “She’ll say they will keep an eye on equity markets and international developments, but say she expects the economy will continue to gain momentum.”

American households are in a good position to bolster growth.

U.S. non-farm payrolls were up 228,000 jobs a month on average in 2015 and rose 151,000 in January. Joblessness dropped to 4.9 percent, a level the Fed considers equivalent to full employment. Average hourly earnings rose the most in a year.