The parameters of the FBI probe don’t include interviewing Julie Swetnick, who said this week the Supreme Court nominee attended a party decades ago where she was gang-raped, according to one of the people.

The focus on the first two accusations suggests that the White House doesn’t consider Ms. Swetnick’s accusations credible, people familiar with the instructions said, a decision that drew criticism from Ms. Swetnick’s attorney, Michael Avenatti.

The Wall Street Journal has attempted to corroborate Ms. Swetnick’s account, contacting dozens of former classmates and colleagues, but couldn’t reach anyone with knowledge of her allegations. No friends have come forward to publicly support her claims.