See Who the Whistleblower May Have Worked With in the White House
A retired CIA officer told the Washington Examiner there's no doubt – based on what is known about the whistleblower's work in the White House – that they worked alongside Biden.
Per the New York Post:
"From everything we know about the whistleblower and his work in the executive branch then, there is absolutely no doubt he would have been working with Biden when he was vice president," the officer, who was not identified by the newspaper, said.
The source added that the whistleblower, who has been identified as a CIA official, likely briefed Biden on issues related to Ukraine and may have accompanied the former vice president on trips he made to the country.
Joseph Maguire, the current intelligence chief, said in a public congressional hearing that he believed the whistleblower acted "in good faith" but could not say he did not have a political bias.
Michael Atkinson, the inspector general of national intelligence, said the whistleblower had a "professional relationship" with a 2020 Democratic presidential candidate.