Treasury 10-year yields traded at the lowest level this year on bets the Federal Reserve will affirm its commitment to the pace of bond purchases to support growth and as the U.S. said it may reduce debt-auction sizes.

"Cutting and tapering QE is not going to be in the cards for quite some time," said Justin Lederer, an interest-rate strategist at Cantor Fitzgerald. "Data continues to be weak. Part of issuing floaters was the expectation that shorter maturities may be cut a little bit. I would be surprised to see longer maturities cut in size."