The dollar jumped to its highest level in over a month.

The US dollar index was up by 0.7% at 93.57 at 8:59 a.m. ET on Wednesday morning, its highest level since August 23.

The index’s climb follows Fed Chair Janet Yellen’s comments Tuesday in Cleveland.

“It would be imprudent to keep monetary policy on hold until inflation is back to 2%,” she said, adding that the Fed “should also be way or moving too gradually.”

Against this backdrop, investors and analysts are increasingly commenting on the uncertainty surrounding Fed leadership as we head into 2018. Fed Vice Chairman Stanley Fischer stepped down in early September, and Bloomberg reported Tuesday that Republican Senator Richard Shelby said he doesn’t think President Donald Trump will nominate Yellen for a second term.

"It's interesting to note though that despite the central banks expectations on interest rates, the dollar hasn't yet recovered significantly from its lows and market pricing of rate hikes next year is far below what the dot plot indicated," said Craig Erlam, senior market analyst at OANDA, in emailed comments.

"Perhaps this reflects a belief that Yellen's term won't be extended beyond February and she will be replaced by someone less inclined to raise interest rates or that inflation expectations are far lower among investors than what the Fed is projecting."

The US dollar index is down by about 9% since Trump's inauguration in January.

As for the rest of the world, here's the scoreboard at 8:59 a.m. ET:

    The euro was down 0.6% at 1.1720 against the dollar.The British pound was weaker by 0.6% at 1.3383 against the dollar.The Japanese yen was lower by 0.8% at 113.19 per dollar.The Indian rupee was off 0.6% at 65.715 per dollar.The Russian ruble was down 0.9% at 57.3408 per dollar.