Also uncertain was the outlook for U.S. interest rates.
Federal Reserve policymakers are still signalling rate increases ahead but also sounded more concerned about a potential global slowdown, leading markets to suspect the tightening cycle may not have much further to run.
Investment bank Goldman Sachs chimed in, saying it expected the pace of U.S. economic growth to slow towards the global average next year.
As a result, it now sees a broad dollar decline next year. It revised its long-standing bearish view on the Japanese yen and tipped Latin American currencies, the Swedish krona, the Canadian, Australian and New Zealand dollars and the Israeli shekel to rise.
"We see several changes to the global economic backdrop which, combined with a few negative medium-run factors, point to more downside than upside to the broad dollar in 2019," Goldman analysts said in a macroeconomic outlook report.
That will focus attention on an appearance by New York Fed President John Williams later on Monday to see if he echoes the same theme.
Investors have already lengthened the odds on further hikes, with a December move now priced at 73 percent, down from over 90 percent. Futures imply rates around 2.74 percent for the end of next year, compared to 2.93 percent early this month.
Yields on U.S. 10-year paper have duly declined to 3.08 percent, from a recent top of 3.25 percent.
The dollar followed to hover at 96.416 against a basket of currencies, down from a peak of 97.693. The euro was parked at $1.1417, while the dollar backed off to 112.72 yen.
Sterling edged higher to $1.2854 after political turmoil over Brexit caused steep losses last week.
British Prime Minister Theresa May said on Sunday that toppling her would risk delaying Brexit as she faces the possibility of a leadership challenge from within her own party.
With both pro-EU and pro-Brexit lawmakers unhappy with the draft agreement, it is not clear that she will be able to win the backing of parliament, increasing the risk that Britain will leave the EU without a deal.
In commodity markets, gold found support from the drop in the dollar and held at $1,1220.19. Oil prices suffered their sixth straight week of losses last week, but have found some support from expectations that the Organization of the Petroleum Exporting Countries will cut output. Brent crude was up 54 cents at $67.30 a barrel, while U.S. crude gained 70 cents to $57.16.
