Some Fed officials have worried investors are underestimating the FOMC’s resolve to continue to tighten gradually. Regional Fed chiefs Eric Rosengren of Boston and Charles Evans of Chicago told investors this month that the committee’s forecast for two more rate increases this year is a solid bet.

Yellen said on March 29 that the FOMC should “proceed cautiously in adjusting policy,” citing global risks including slowing growth in China and the outlook for commodity prices, which have hurt business investment in the U.S. and some emerging markets.

The global economy remains a source of concern. The International Monetary Fund on April 12 cut its estimate for global growth to 3.2 percent this year from 3.4 percent in January, and warned of a risk of global stagnation.

Brexit Threat, GDP Report

A new threat may be the U.K.’s June referendum on whether to stay in the European Union, which Atlanta Fed President Dennis Lockhart said on April 14 would be “a big event” and “a consideration” for U.S. monetary-policy makers.

“Global risks are here to stay although the seas are calmer around the globe at the moment,” said Chris Rupkey, chief financial economist with Bank of Tokyo-Mitsubishi UFJ Ltd. in New York. He sees the statement doing little to signal June is on the table.

“Caution is likely to rule the board and bank presidents,” Rupkey said, referring to the Fed’s Board of Governors. “They aren’t in any hurry.”

A further complication is that any upgrade in the statement language comes as U.S. has stalled. The U.S. economy probably grew at a 0.6 percent annual rate in the first quarter, according to economists surveyed by Bloomberg, and the Atlanta Fed’s estimate is just 0.3 percent. The government will release the preliminary gross domestic product report on Thursday, just a day after the FOMC meeting.

Despite the weakness, the FOMC may strive to make few changes to its economic assessment while highlighting continued improvement in the labor market, said Millan Mulraine, deputy head of U.S. research and strategy at TD Securities USA LLC in New York. The group may continue to describe growth as “moderate,” he said.

“They expect growth to rebound after the first quarter, so they wouldn’t want to be overly pessimistic as they believe this will be reversed,” he said.