The Justice Department has subpoenaed the Nevada secretary of state for voter information, according to a person familiar with the operation, at a time when the government is rapidly escalating efforts to prove President Trump’s baseless claims of voter fraud. The office of Cisco Aguilar, Nevada’s secretary of state and its chief election officer, confirmed receiving seven “voter-related” subpoenas from F.B.I. agents over the last three months, but declined to offer details. It is unclear whether other states have received similar subpoenas.

The U.S. attorney in Nevada, Sigal Chatta, whose office would have overseen the request, is a pro-Trump prosecutor who has repeatedly sought to cast doubt on the integrity of federal elections. With less than 60 days to go before the midterm elections, the Trump administration has deployed hundreds of investigators to hunt for voter fraud, despite decades of evidence that it is exceptionally rare in the United States.

“The right to vote is written clearly in the Constitution, and we cannot take that right away without the highest confidence of a person’s ineligibility,” Mr. Aguilar said in a statement. “The federal administration is inundating election offices with investigations and questions ahead of the election, and making sweeping claims of election fraud to the public before any investigation is done.”

Roughly two dozen states have sued the administration over some of those actions. The subpoenas follow previous efforts by the Justice Department to obtain private voter information. In December, the Justice Department sued Nevada and 29 other states, demanding unredacted voter files. Judges have tossed 23 of these lawsuits. The administration has also asked the Supreme Court to restrict mail voting and enlisted federal agencies to find noncitizen voters.