House Republicans have snagged high-profile witnesses for a Sept. 18 hearing on the White House’s new climate plan: Environmental Protection Agency Administrator Gina McCarthy and Energy Secretary Ernest Moniz.

The Energy and Commerce Committee last month asked 13 federal agencies to send their top official or a designee to testify. The EPA and the Energy Department both went with their leaders, a committee aide said Wednesday.

But Energy and Power subcommittee Chairman Ed Whitfield (R-Ky.) appears to have gotten an underwhelming response from other agencies. McCarthy and Moniz are the only witnesses confirmed to date, the aide said.

Whitfield on Wednesday sent follow-up letters to other agencies, such as the Interior, Agriculture and Transportation departments, seeking witnesses for the hearing.

“We remain hopeful each agency will be able to provide a witness as the initial request was sent over six weeks ahead of the September 18 hearing,” the committee aide said.