The new Navarro subpoena, and another grand jury subpoena issued to Patrick Gartland, who was considering but ultimately declined to serve as a alternate Trump slate elector from Georgia, shows the grand jury is delving into efforts to force a delay in the certification of Joe Biden’s victory on Jan. 6, including involvement by several top Trump allies.

Among people listed as contacts of interest in Gartland’s subpoena are former Trump legal advisers Rudy Giuliani, Jenna Ellis, and John Eastman. Giuliani and Eastman have been previously depicted by the House committee as central figures in the plan and Ellis also has been described by the committee as having prepared and circulated memos about the effort.

The plan involved creation of false elector slates and certificates declaring Trump the winner of Electoral College votes in seven battleground states that Joe Biden actually won — Arizona, Georgia, Michigan, New Mexico, Nevada, Pennsylvania and Wisconsin. These were then sent to the National Archives and other government officials in mid-December 2020, along with supporting documents.

Meanwhile, Navarro is separately battling a contempt of Congress count lodged against him by a House vote on April 6 for defying an earlier subpoena from the committee investigating the Jan. 6, 2022 insurrection at the US Capitol. His refusal has been referred to the Department of Justice for prosecution. Whether the grand jury seeking Navarro’s testimony is focused on strictly his congressional criminal contempt case — or broader Trump-inner circle activities — is not immediately clear.

Navarro, in the lawsuit filed Tuesday in US District Court in Washington, asserts that the nine-member House committee is not properly authorized or constituted and thus its legislative acts, including the committee subpoena he defied, are invalid. He also calls the subpoena from the federal grand jury as a resulting legal “fruit of the poisonous tree.”

The House committee had no comment on Navarro’s lawsuit, said spokesman Tim Mulvey.