More: The remarks, made during testimony before the Senate Judiciary Committee, stood at odds with earlier comments indicating that he did not intend to send federal agents to polling places around the country. However, when Senator Peter Welch, Democrat of Vermont, pressed the issue, Mr. Patel seemed to reverse course.

"I thought you weren't going to be sending people to the polls," Mr. Welch said.

"When did you hear that? Just another lie," Mr. Patel declared, raising his voice.

Mr. Welch revisited the issue. "So you are sending F.B.I. agents to the polls?"

"We have election crisis coordinators manned at all 56 field offices," Mr. Patel replied, appearing to refer to what are known as election crime coordinators. "Election integrity is of paramount importance. This F.B.I. will not shy away from that effort."

Under the law, armed federal officers or military personnel are barred from being deployed "at any place where a general or special election is held." The chairman of the Joint Chiefs of Staff said in a letter to a Democratic senator last month that there were "no plans" for the armed forces to deploy troops to polling stations for the midterm elections.