Democrats are asking Barr in a letter why the Justice Department decided to start executions and who was consulted. While the death penalty remains legal in many states, federal executions are rare.
The Democrats raised questions about the lethal drug pentobarbital sodium that will likely be used amid problems reported at some manufacturers.
Rep. Jamie Raskin of Maryland, the chairman of a subcommittee on civil rights, and Rep. Ayanna Pressley of Massachusetts wrote they are "extremely concerned."
Barr announced last month the federal government was ending the informal moratorium despite the national shift away from capital punishment.
Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.