A voting member this year on the central bank's policymaking committee, Bullard said in a speech Wednesday evening that he continues to oppose further rate hikes, due to what he called "declining market-based inflation expectations."
A longtime hawkish member of the Federal Reserve who had pushed for higher rates, Bullard first reversed course in a separate address last week, when he raised a red flag about the lack of price pressures.
Market participants tend to agree with Bullard, with expectations for further rates severely dampened by the financial turmoil of 2016.
Explaining his inflation concerns, Bullard told CNBC Thursday he had thought last year that once oil prices stabilized inflation expectations would increase.
"But then starting in November, we had another leg down in the oil markets," he said. "This is too low for comfort, and it's giving me pause."
"The stories I'm telling about declining inflation expectations being concerning do not have to do with the economy in the tank. I don't really think so," he added.