The dollar index, which measures the greenback against a basket of six major currencies, was last down 0.23 percent at 98.494 after touching 99.119 on Tuesday, its highest since Feb. 1. The index has risen about 3.2 percent this month, putting it on track for its best month in nearly a year.
"The dollar is vulnerable to downside," said Douglas Borthwick, managing director at Chapdelaine Foreign Exchange in New York. "What's priced into it is a Fed rate rise in December, a [Hillary] Clinton victory, and neither of these is 100 percent guaranteed."
He said a potential surprise victory for U.S. Republican presidential candidate Donald Trump would hurt the dollar.
Traders saw a 74 percent chance that the Fed would hike rates in December on Wednesday, down from a more than 78 percent chance on Tuesday, according to CME Group's FedWatch program.
The euro was last up 0.22 percent against the dollar at $1.0909 after touching a six-day high of $1.0945 earlier in U.S. trading. That marked a rebound from a 7-1/2-month low of $1.0848 touched on Tuesday.