"The trade conflicts and tensions, the (U.S. government) shutdown and certainly more chatter about global growth in 2019, those are the factors that need to be hashed out before we get a clear direction," said Minh Trang, senior currency trader at Silicon Valley Bank in Santa Clara, California.
On Monday, the International Monetary Fund cut its 2019 and 2020 global growth forecasts, citing a bigger-than-expected slowdown in China and the euro zone. Failure to resolve trade tensions could further destabilize the global economy, the IMF said.
The partial U.S. government shutdown, now in its 33rd day, added to investors' unease. U.S. Republican Senate Majority Leader Mitch McConnell said he planned to hold a vote on Thursday on a Democratic proposal that would fund the government for three weeks.
"People are a little bit cautious in terms of putting on excessive positions in any one direction," said Trang.
The dollar index, which tracks the greenback versus the euro, yen, sterling and three other currencies, was down 0.18 percent at 96.13. The index has risen nearly 1 percent over the last two weeks.
"The USDs rebound from its January 9 low seems complete as incoming U.S. economic data indicates weakness, especially in rate-sensitive sectors like housing and corporate investment," Hans Redeker, global head of FX strategy, at Morgan Stanley, wrote in a client note.
The greenback was up 0.2 percent against the yen after the Bank of Japan on Wednesday kept its stimulus program in place.
The BOJ cut its inflation forecasts but maintained its stimulus program, with Governor Haruhiko Kuroda warning of growing risks to the economy from trade protectionism and faltering global demand.
"They are conceding that the risks to inflation and growth are skewed to the downside," said Trang.
Currency traders' attention now shifts to the European Central Bank, which meets on Thursday where market watchers expect it to acknowledge growing threats to the euro zone economy.
Sterling leaped to a 10-week high after Britain's opposition Labour Party said it would back an attempt by lawmakers to prevent a disorderly no-deal Brexit.
The United Kingdom is due to leave the European Union on March 29 but has no approved deal on how the divorce will take place.