ANAHEIM, Calif. — Senator Bernie Sanders may be trailing Hillary Clinton by hundreds of delegates, and Mrs. Clinton may be treating the Democratic nomination as hers, but Julie Crowell, a stay-at-home mother and a die-hard Sanders supporter, is holding out for an 11th-hour miracle: divine deliverance at the hands of the F.B.I.

Like many of Mr. Sanders’s supporters, Ms. Crowell, 37, said she hoped that Mrs. Clinton’s use of a private email server during her time as secretary of state would eventually yield an indictment, and she described it as the kind of transgression that would disqualify another politician seeking high office.

“She should be removed,” said Ms. Crowell, of Tustin, Calif., who attended a Sanders rally here on Tuesday and said she planned to vote for a third-party candidate if Mr. Sanders failed to overtake Mrs. Clinton and capture the Democratic nomination. “I don’t know why she’s not already being told, ‘You can’t run because you’re being investigated.’ I don’t know how that’s not a thing.”

Campaigning in California, where polls show a tightening primary race, Mr. Sanders continued to hit Mrs. Clinton over her positions on Wall Street, trade deals, the minimum wage, hydrofracking and “super PACs” — seemingly everything except her emails, which he took off the table as an issue during an early Democratic debate. But Mrs. Clinton faces renewed criticism after an inspector general’s report faulted her for violating the State Department’s records-retention policy. And as the F.B.I. continues to investigate the handling of classified information, attendees at Sanders rallies have repeatedly expressed hope that the scandal results in criminal charges.