WASHINGTON—U.S. officials have put off until at least Monday plans to file charges against Dzhokhar Tsarnaev, the surviving suspect in the Boston Marathon bombings, a U.S. official said.

Earlier, officials had said they were preparing for a possible filing of charges Sunday but cautioned that the timing was fluid because of Mr. Tsarnaev's medical issues. Officials said the 19-year-old was drifting in and out of consciousness at a hospital after being shot in the throat during a confrontation with authorities early Friday morning....