Hillary Clinton's opinion research director blamed the Democratic presidential hopeful's stunning defeat in Tuesday's election on FBI Director James Comey, in an email on Friday to senior staffers who were involved with her campaign.

"We believe that we lost this election in the last week," Navin Nayak wrote to his colleagues, in an email obtained by Politico. "Comey's letter in the last 11 days of the election both helped depress our turnout and also drove away some of our critical support among college-educated white voters — particularly in the suburbs.

"We also think Comey's 2nd letter, which was intended to absolve Sec. Clinton, actually helped to bolster Trump's turnout," he added.

Less than two weeks before Election Day, Comey sent a letter to congressional committee chairs informing them that the FBI had reopened its investigation into Clinton's private email server. The agency's decision gave Donald Trump an opportunity to capitalize on questions surrounding Clinton's judgment and to prosecute the case against her more vigorously than he had before.

Two days before the Nov. 8 election, Comey sent a follow-up letter to members of Congress in which he stood by his previous decision to forego recommending criminal charges against the former secretary of state.

"[E]verything changed in the last week," Nayak wrote in his email, noting that voters who decided which candidate to support in the final few days before the election "broke for Trump by a larger margin (42-47).

"These numbers were even more exaggerated in the key battleground states," he acknowledged.

"There is no question that a week from Election Day, Sec. Clinton was poised for a historic win," Nayak said. "In the end, late breaking developments in the race proved one hurdle too many for us to overcome."

Nayak also said Trump benefited from voters' overwhelming frustration with the existing political system and a desire for change after "one party occupie[d] the White House for two terms."