Treasurys sold off slightly in Monday morning trading, but held on to the bulk of Friday's rally, as strategists raised questions about whether a September interest-rate cut from the Federal Reserve can actually happen.

Jay Powell set the stage for a reduction in borrowing costs but jobs and inflation reports could get in the way

Major brokerages, including Barclays, BNP Paribas and Deutsche Bank, now expect a 25-basis-point U.S. Federal Reserve rate cut in September following Chair Jerome Powell's shift in tone at Jackson Hole toward rising risks in the labor market.